0:00:04 > 0:00:08In the act of murder, there is a weapon...
0:00:10 > 0:00:12GUNSHOT
0:00:12 > 0:00:13..a crime scene...
0:00:16 > 0:00:17..and a body.
0:00:19 > 0:00:23All vital evidence in the hunt for the killer.
0:00:26 > 0:00:29It's a game of cat and mouse between police and murderer
0:00:29 > 0:00:32that used to favour the criminal,
0:00:32 > 0:00:37but then something happened that swung the odds in favour of justice.
0:00:39 > 0:00:42The arrival of forensic science.
0:00:47 > 0:00:49I'm Gabriel Weston.
0:00:49 > 0:00:51As a surgeon and writer,
0:00:51 > 0:00:55I'm fascinated by the work of the forensic scientist
0:00:55 > 0:00:58and the murders they've helped to solve.
0:01:02 > 0:01:03In this series...
0:01:05 > 0:01:09..I'll explore the cases that transformed criminal investigation.
0:01:11 > 0:01:13Through poison and acid...
0:01:15 > 0:01:17..fingerprints and blood...
0:01:19 > 0:01:21..from the earliest days,
0:01:21 > 0:01:24to the cutting edge of modern forensics.
0:01:29 > 0:01:32This is the story of the crime scene...
0:01:33 > 0:01:35..four murders which reveal
0:01:35 > 0:01:39how science became central to crime scene investigation.
0:01:41 > 0:01:43But it's a troubled history.
0:01:45 > 0:01:48The science is improving all the time
0:01:48 > 0:01:51and can tell us more and more about what happened,
0:01:51 > 0:01:54where, to whom and who did it.
0:01:54 > 0:01:58But the science has to be applied by humans -
0:01:58 > 0:02:03and humans always have been and always will be far from perfect.
0:02:17 > 0:02:19In June of 1908,
0:02:19 > 0:02:23the police in the small town of Rockenhausen, Bavaria, were stuck.
0:02:25 > 0:02:28The body of a woman in her early thirties -
0:02:28 > 0:02:32an unmarried housekeeper, elegantly dressed -
0:02:32 > 0:02:34had been discovered in the woods.
0:02:37 > 0:02:41Margarethe Filbert had been strangled and decapitated
0:02:41 > 0:02:44and her head was nowhere to be found.
0:02:44 > 0:02:47Now, in this small, tightly-knit, rural community,
0:02:47 > 0:02:49everyone knew everyone else
0:02:49 > 0:02:51and the investigation was only a few days old
0:02:51 > 0:02:56when the police realised they had a suspect firmly in their sights.
0:02:56 > 0:02:58There was only one problem.
0:02:58 > 0:03:01They had absolutely no evidence.
0:03:08 > 0:03:10Nobody had witnessed the murder,
0:03:10 > 0:03:14but as the police knocked on doors and asked questions,
0:03:14 > 0:03:18one name cropped up again and again -
0:03:18 > 0:03:21that of a local farmer, Andreas Schleicher.
0:03:22 > 0:03:24They paid him a visit.
0:03:24 > 0:03:29Schleicher simply denied all knowledge of the crime.
0:03:29 > 0:03:32The police asked to see the clothes he'd worn that day,
0:03:32 > 0:03:36because the killer's clothing must have been drenched in blood.
0:03:37 > 0:03:39But the jacket and trousers seemed clean.
0:03:40 > 0:03:44The shoes had some mud on the soles, but why shouldn't they?
0:03:44 > 0:03:46Schleicher lived on a farm.
0:03:47 > 0:03:51He insisted he'd spent the whole day in his own fields.
0:03:52 > 0:03:54That was his story, and he stuck to it.
0:03:56 > 0:04:01But the police took the clothes and shoes away, just in case.
0:04:02 > 0:04:05They were certain he was Margarethe's murderer,
0:04:05 > 0:04:08but all they had was gossip and hearsay.
0:04:10 > 0:04:12They needed evidence.
0:04:17 > 0:04:22The idea that science had something to offer crime investigations
0:04:22 > 0:04:26had been gently stewing in Europe for at least 20 years,
0:04:26 > 0:04:30ever since Conan Doyle had first had Sherlock Holmes
0:04:30 > 0:04:33make his collections of different cigar ashes.
0:04:35 > 0:04:36Whole books had been written
0:04:36 > 0:04:41about the ways in which science could shed light on criminal cases
0:04:41 > 0:04:44and it was the local District Attorney who remembered
0:04:44 > 0:04:48that there was a chemist in Frankfurt, Georg Popp,
0:04:48 > 0:04:50who had helped the police before.
0:04:51 > 0:04:53He sent Popp a telegram.
0:04:56 > 0:04:59Popp's normal business was more ordinary.
0:04:59 > 0:05:02His company specialised in food hygiene
0:05:02 > 0:05:04and the purity of mineral water.
0:05:04 > 0:05:07Crime science was just a sideline.
0:05:07 > 0:05:09But for Popp, it was also a passion.
0:05:11 > 0:05:14He replied to the telegram at once.
0:05:14 > 0:05:18Yes, he would be more than happy to help,
0:05:18 > 0:05:21but the police weren't happy to have him.
0:05:21 > 0:05:24They resented the meddling District Attorney
0:05:24 > 0:05:27inviting this amateur to get involved
0:05:27 > 0:05:30and repeatedly refused Popp's requests
0:05:30 > 0:05:32that they send him the clothes and shoes.
0:05:34 > 0:05:38Instead, they searched the valley again and again,
0:05:38 > 0:05:42looking for Margarethe's purse, her parasol
0:05:42 > 0:05:44and her severed head.
0:05:51 > 0:05:53In the cellars of a ruined castle
0:05:53 > 0:05:55they found a secret cache,
0:05:55 > 0:06:00including a shotgun and some trousers which were damp,
0:06:00 > 0:06:01but apparently free of blood.
0:06:03 > 0:06:07Could these items have anything to do with the murder?
0:06:07 > 0:06:10Could they belong to Schleicher?
0:06:10 > 0:06:13Once again, Schleicher denied all knowledge.
0:06:18 > 0:06:21Several weeks after the discovery of the secret cache,
0:06:21 > 0:06:27a lowly constable was inspired to turn the trousers inside out.
0:06:29 > 0:06:31Once word got around,
0:06:31 > 0:06:34the police were a laughing stock.
0:06:34 > 0:06:40Now, the District Attorney insisted that Popp must be involved.
0:06:40 > 0:06:43At long last, the clothes and shoes were sent to Georg Popp
0:06:43 > 0:06:46in his Frankfurt laboratory.
0:06:46 > 0:06:49Margarethe Filbert had been dead two months.
0:06:54 > 0:06:57Popp began with some chemical tests
0:06:57 > 0:07:00and made his first revelation.
0:07:00 > 0:07:02Schleicher's jacket and trousers
0:07:02 > 0:07:06were indeed both stained with human blood.
0:07:06 > 0:07:11A good start, but there was no way to prove whose blood it was.
0:07:11 > 0:07:14It didn't connect Schleicher to Margarethe,
0:07:14 > 0:07:18so Popp stopped looking at the clothing
0:07:18 > 0:07:20and he started looking at the shoes.
0:07:23 > 0:07:26And he had a simple but amazing insight
0:07:26 > 0:07:29that would prove pivotal to the case.
0:07:30 > 0:07:33It occurred to him that the mud on Schleicher's shoes
0:07:33 > 0:07:37was a record of where he'd been on the day of the murder.
0:07:39 > 0:07:41I'm in a muddy spot here, myself.
0:07:41 > 0:07:45There's mud all around me at my feet,
0:07:45 > 0:07:49it's squelchy and there's all sorts of stuff
0:07:49 > 0:07:53growing in and around the mud - there's moss and plants.
0:07:53 > 0:07:57There's twigs and all sorts of rotted matter.
0:07:57 > 0:08:02It's evident, then, that if I were standing here for any time at all,
0:08:02 > 0:08:06I'd be gathering evidence of this mud all over my footwear.
0:08:12 > 0:08:14Popp had good reason to think
0:08:14 > 0:08:18that the shoes held the evidence he needed.
0:08:18 > 0:08:20He knew the police had had them
0:08:20 > 0:08:24unworn and uncleaned since the murder.
0:08:24 > 0:08:26He knew that Schleicher insisted
0:08:26 > 0:08:30he'd only walked in his own fields on that day.
0:08:30 > 0:08:32But what if the mud on the shoes
0:08:32 > 0:08:35could prove he'd walked somewhere else entirely?
0:08:37 > 0:08:41Late in September, Popp travelled to the valley.
0:08:41 > 0:08:42He collected soil samples
0:08:42 > 0:08:46from every location that was connected to the case.
0:08:48 > 0:08:53Popp compared these soil samples with the mud on Schleicher's shoes.
0:08:53 > 0:08:58First, he had to cut into the mud to make a section from top to bottom.
0:09:00 > 0:09:04Now, I'm a surgeon and like to think I have a steady hand.
0:09:04 > 0:09:06Let's see how I get on with this task.
0:09:13 > 0:09:15It's very difficult.
0:09:15 > 0:09:17It crumbles incredibly easily.
0:09:18 > 0:09:21All I can get off is these chunks.
0:09:25 > 0:09:28Popp was more successful
0:09:28 > 0:09:32and what he learnt from his microscopic analysis was this -
0:09:32 > 0:09:37he found nothing that resembled the soil of Schleicher's fields.
0:09:37 > 0:09:42Instead, stuck directly to the sole itself were goose droppings,
0:09:42 > 0:09:45like those outside Schleicher's house.
0:09:46 > 0:09:48They must have got onto the shoe first.
0:09:49 > 0:09:52Then, a second layer contained grass,
0:09:52 > 0:09:56like the meadows on the way to the woods where the body was found.
0:09:58 > 0:10:01The third layer was a sandy soil,
0:10:01 > 0:10:06flecked with granules of quartz and specks of leaf mould,
0:10:06 > 0:10:09exactly like the soil where Margarethe's body had been found.
0:10:11 > 0:10:14And the final, outermost layer
0:10:14 > 0:10:17was a soil containing fragments of dust,
0:10:17 > 0:10:19exactly like the castle cellar
0:10:19 > 0:10:22where the secret cache had been discovered.
0:10:23 > 0:10:28By now, he had connected Schleicher with the crime scene,
0:10:28 > 0:10:31but he didn't stop there.
0:10:31 > 0:10:34In the third layer, he found tiny fibres -
0:10:34 > 0:10:38wool and cotton, reddish brown.
0:10:38 > 0:10:41And in the fibres of Margarethe's petticoat,
0:10:41 > 0:10:43he found a perfect match.
0:10:45 > 0:10:47He'd established that Schleicher
0:10:47 > 0:10:50hadn't visited his own fields at all that day.
0:10:51 > 0:10:55Popp's analysis had tracked him all the way to the scene of the crime,
0:10:55 > 0:10:57to the secret cache in the cellar
0:10:57 > 0:11:02and had proved that he had even stood on Margarethe's petticoat.
0:11:02 > 0:11:06The soil on his shoes had shown he was the killer.
0:11:10 > 0:11:12Schleicher was jailed.
0:11:12 > 0:11:16After a year behind bars, he confessed.
0:11:16 > 0:11:20He'd killed Margarethe because she looked well off,
0:11:20 > 0:11:22then found her purse was empty
0:11:22 > 0:11:25and cut her head off in a fit of rage.
0:11:27 > 0:11:29He told the police where it was hidden.
0:11:35 > 0:11:39Georg Popp had invented a new discipline -
0:11:39 > 0:11:40forensic geology.
0:11:43 > 0:11:46To see what's possible today,
0:11:46 > 0:11:48after filming for this story,
0:11:48 > 0:11:50I sent my Wellington boots by courier
0:11:50 > 0:11:53to a forensics laboratory in Aberdeen.
0:11:55 > 0:12:00We filmed this story in Mugdock Country Park, north-west of Glasgow,
0:12:00 > 0:12:02and I want to see if the scientists,
0:12:02 > 0:12:06using the mud stuck to my boots and nothing else,
0:12:06 > 0:12:12can tell me exactly where in Scotland's 78,000 square kilometres
0:12:12 > 0:12:14that muddy evidence came from.
0:12:22 > 0:12:25'At the Hutton Institute Labs in Aberdeen,
0:12:25 > 0:12:28'one of my boots is having its mud removed for analysis.'
0:12:31 > 0:12:34You can tell specifics about what those species are....
0:12:34 > 0:12:36'Professor Lorna Dawson and her team
0:12:36 > 0:12:40'have instruments and techniques at their disposal
0:12:40 > 0:12:42'which Popp could only have dreamt of.
0:12:43 > 0:12:45'After two days of tests,
0:12:45 > 0:12:49'Lorna takes her new data to her colleague, David Miller.'
0:12:50 > 0:12:53So, we use the national mapping of resources of Scotland....
0:12:53 > 0:12:55'David has maps of Scotland
0:12:55 > 0:12:58'which contain information about minerals,
0:12:58 > 0:13:01'plant distribution and the soil itself.
0:13:04 > 0:13:05'But have they learnt enough
0:13:05 > 0:13:08'to tell me where the mud on my boots came from?
0:13:10 > 0:13:12'It's a process of elimination.'
0:13:14 > 0:13:16Lorna, can you give me
0:13:16 > 0:13:18some idea of what we're going to be looking for first,
0:13:18 > 0:13:20or what we cannot be looking at?
0:13:20 > 0:13:23Well, what we knew from the gas chromatography.....
0:13:24 > 0:13:28'The first result arose from gas chromatography,
0:13:28 > 0:13:33'which analyses traces of organic matter and chemicals.
0:13:33 > 0:13:36'It revealed the absence in our sample of this
0:13:36 > 0:13:41'pink line of hydrocarbon pollution, caused by cars.
0:13:41 > 0:13:43'We didn't film in a town or city.'
0:13:48 > 0:13:51- So we exclude the urban areas of Scotland.- OK.
0:13:51 > 0:13:54So, that's all the black areas now, are not part of the search?
0:13:54 > 0:13:57Yes, exactly. Next...
0:13:57 > 0:14:01'Using techniques that Popp would have been very comfortable with,
0:14:01 > 0:14:03'Lorna studied the soil itself
0:14:03 > 0:14:07'and the botanical traces it contains under a microscope.'
0:14:08 > 0:14:12You can see that there's a fibrous texture to that soil.
0:14:12 > 0:14:15It's got very small granular structure.
0:14:15 > 0:14:17It's not a single grain,
0:14:17 > 0:14:20as you would find generally in an arable soil.
0:14:20 > 0:14:23It's not got the peat fibres that you would expect in a peatland.
0:14:25 > 0:14:30'So, Lorna concluded that we didn't film in peatlands and uplands -
0:14:30 > 0:14:32these purple sections.
0:14:33 > 0:14:37'And she excludes all of Scotland's arable land,
0:14:37 > 0:14:40'in light green, from the central belt to the north-east.
0:14:42 > 0:14:45'But Lorna did find fragments of beech leaves.
0:14:46 > 0:14:48'Gas chromatography confirmed
0:14:48 > 0:14:53'there were no chemicals connected with pines and conifers.
0:14:53 > 0:14:55'It's deciduous forest they're looking for.
0:14:57 > 0:15:01'Scotland's pine forests, in dark green, are eliminated.'
0:15:04 > 0:15:06We're really narrowing down now,
0:15:06 > 0:15:09to really what looks like a tiny amount left of Scotland,
0:15:09 > 0:15:12where this could have been, this walk.
0:15:12 > 0:15:15- Well, we hope it is. - LAUGHTER
0:15:15 > 0:15:18So, you were telling me something about the underlying geology.
0:15:21 > 0:15:27'Lorna's team has two powerful resources for geological analysis.
0:15:27 > 0:15:31'X-ray crystallography identifies the minerals found on my boot
0:15:31 > 0:15:33'by their crystal structure...
0:15:35 > 0:15:40'..and the National Soil Archive - soils from all over Scotland -
0:15:40 > 0:15:42'has been used to make a database
0:15:42 > 0:15:46'for comparison with crime scene samples.
0:15:46 > 0:15:48'In our case, the results point to
0:15:48 > 0:15:52'an area of volcanic soils that surrounds Glasgow.'
0:15:55 > 0:15:57So, the area we're zooming in
0:15:57 > 0:16:01is to the north and the west of Glasgow, here....
0:16:01 > 0:16:04'Now they're looking not at where I wasn't,
0:16:04 > 0:16:06'but at where I was.'
0:16:06 > 0:16:08..Then what we're interested in are the areas...
0:16:08 > 0:16:11'Lorna and David's software highlights areas in yellow
0:16:11 > 0:16:14'where the right kind of volcanic soil
0:16:14 > 0:16:16'can be found with deciduous trees.'
0:16:17 > 0:16:20Look just a little bit to the north of Glasgow,
0:16:20 > 0:16:24there's quite a big area here which fits the characteristics......
0:16:24 > 0:16:28'They soon home in on a place that looks very familiar.'
0:16:28 > 0:16:31It's got the right soil characteristics and....
0:16:31 > 0:16:34'I think I'm about to be astonished.'
0:16:34 > 0:16:36That could be an area that you picked up the soil and that
0:16:36 > 0:16:39would certainly be an area that we'd prioritise to the police to search.
0:16:39 > 0:16:40And where is this area?
0:16:42 > 0:16:45This is Mugdock Castle, at Mugdock Country Park,
0:16:45 > 0:16:47just north of Glasgow, that we're looking at just now.
0:16:47 > 0:16:50- Mugdock Loch. - I'm completely blown away.
0:16:50 > 0:16:53Absolutely amazing, it's exactly where we were.
0:16:53 > 0:16:55- Was that where you were? - Exactly where we were.
0:16:55 > 0:16:59So, out of 78,000 square kilometres, to what -
0:16:59 > 0:17:01what would this area be?
0:17:01 > 0:17:05This area will be a few hundred square metres.
0:17:05 > 0:17:07- Amazing.- Can you point where you walked?
0:17:07 > 0:17:09- Well, we were right by the castle... - Gosh.
0:17:09 > 0:17:13..and we went down into the forest, there was a valley...
0:17:16 > 0:17:21Lorna and her team would certainly have caught Schleicher too.
0:17:21 > 0:17:24Crime scenes stick to criminals,
0:17:24 > 0:17:27and Georg Popp was one of the first to prove it.
0:17:30 > 0:17:34After Popp, criminals would have to contend with investigations
0:17:34 > 0:17:36that could determine what they'd done
0:17:36 > 0:17:40and even where they'd been with ever greater clarity.
0:17:40 > 0:17:42With the help of scientific techniques,
0:17:42 > 0:17:45crimes that might have taken months to solve -
0:17:45 > 0:17:47if they'd ever been solved at all -
0:17:47 > 0:17:52could sometimes be done and dusted in just a few days.
0:17:52 > 0:17:53ENGINE STARTS
0:17:57 > 0:18:00Within three decades,
0:18:00 > 0:18:05one such crime was to prove just how far crime scene analysis had come.
0:18:10 > 0:18:12Manhattan, New York.
0:18:12 > 0:18:1510th April, 1936.
0:18:18 > 0:18:20Good Friday.
0:18:20 > 0:18:24Theodore Kruger and his employee John Fiorenza
0:18:24 > 0:18:28were delivering a reupholstered chair to one of their customers.
0:18:30 > 0:18:33The third floor apartment at 22 Beekman Place
0:18:33 > 0:18:37was home to Lewis and Nancy Titterton.
0:18:37 > 0:18:38He was a publisher.
0:18:38 > 0:18:41She was an aspiring crime writer,
0:18:41 > 0:18:43who usually worked at home.
0:18:46 > 0:18:49They had an appointment with Mrs Titterton,
0:18:49 > 0:18:52but there'd been no answer when they rang the bell.
0:18:52 > 0:18:55The street door, however, was open -
0:18:55 > 0:18:59so Kruger and Fiorenza had climbed the stairs
0:18:59 > 0:19:02to find the apartment door was open too.
0:19:03 > 0:19:05Why wasn't she here?
0:19:06 > 0:19:09Kruger pushed the door open and they carried the seat inside.
0:19:09 > 0:19:12At the very least, they could put it back where it belonged,
0:19:12 > 0:19:13in the living room.
0:19:20 > 0:19:23There was no sign of Mrs Titterton.
0:19:23 > 0:19:25Kruger decided to leave a note for her
0:19:25 > 0:19:28and in looking around for pen and paper,
0:19:28 > 0:19:31the two men glanced into the bathroom.
0:19:32 > 0:19:35There, Kruger saw Nancy Titterton
0:19:35 > 0:19:38and why she hadn't answered.
0:19:40 > 0:19:45She lay in the bathtub, with a piece of clothing tied round her neck.
0:19:45 > 0:19:47She was dead.
0:19:57 > 0:19:58Anyone could have killed her.
0:20:00 > 0:20:04It was the sort of crime that might once have defied solution,
0:20:04 > 0:20:07but by 1936,
0:20:07 > 0:20:09wherever there was a large, modern city
0:20:09 > 0:20:12with a well-funded police force,
0:20:12 > 0:20:14there were crime scene investigators.
0:20:15 > 0:20:20The New York Police Department had its own crime scientists on staff
0:20:20 > 0:20:23and the Chief Medical Officer had a team as well.
0:20:24 > 0:20:27Soon, men from both appeared on site.
0:20:30 > 0:20:33Nancy had been strangled with her own pyjama top.
0:20:35 > 0:20:38When her body was lifted from the bathtub,
0:20:38 > 0:20:41a 13 inch length of cord was revealed.
0:20:43 > 0:20:45Nancy's wrists had been bound
0:20:45 > 0:20:49and the killer had tried to remove the evidence,
0:20:49 > 0:20:52unaware that this section lay beneath her body.
0:20:54 > 0:20:56It was string, really.
0:20:56 > 0:21:00Nothing fancy, just a piece of binding twine.
0:21:00 > 0:21:03Clearly, the murderer had brought it here,
0:21:03 > 0:21:06but leaving it behind wasn't part of the plan.
0:21:06 > 0:21:10But could it tell the investigators anything more?
0:21:10 > 0:21:12It was sent to the laboratories
0:21:12 > 0:21:14of the Chief Medical Officer for analysis.
0:21:17 > 0:21:21The rest of the crime scene was secured and analysed.
0:21:22 > 0:21:25The carpets, the bedclothes
0:21:25 > 0:21:27and even the bed itself
0:21:27 > 0:21:30were taken away for microscopic scrutiny.
0:21:33 > 0:21:36Their attention to detail soon paid off.
0:21:37 > 0:21:40In the bedclothes they found a single hair,
0:21:40 > 0:21:44about half an inch long, too stiff to be human
0:21:44 > 0:21:47and too heavy to have blown into the room on its own.
0:21:47 > 0:21:50When they examined it under a microscope,
0:21:50 > 0:21:52they found it was horsehair -
0:21:52 > 0:21:55commonly used for padding seats.
0:21:57 > 0:22:00Attention turned at once
0:22:00 > 0:22:04to the two men who claimed they'd only discovered the body.
0:22:04 > 0:22:07But if one of them had transferred it to the bedclothes,
0:22:07 > 0:22:09when had that happened?
0:22:09 > 0:22:12Kruger said he'd only glanced through the door.
0:22:12 > 0:22:14As for the cord,
0:22:14 > 0:22:18on 17th April, about a week after Nancy's death,
0:22:18 > 0:22:21careful microscopic analysis showed
0:22:21 > 0:22:24it was indeed highly unusual.
0:22:24 > 0:22:26Made mainly of hemp and jute,
0:22:26 > 0:22:30it also contained a rare fibre called istle.
0:22:34 > 0:22:37In the three states closest to Manhattan,
0:22:37 > 0:22:40there were 25 manufacturers of rope and cord.
0:22:42 > 0:22:44The NYPD telegraphed them all.
0:22:46 > 0:22:51Only one, the Hanover Cordage Company of York Pennsylvania,
0:22:51 > 0:22:54responded that it made cord containing istle.
0:22:56 > 0:22:59Officers took the cord to the company for comparison.
0:23:01 > 0:23:04Although it had expanded in the bathwater,
0:23:04 > 0:23:07it was clearly identical to the company's product.
0:23:07 > 0:23:10Officers then asked to see the company's dispatches
0:23:10 > 0:23:12and found that some of the cord
0:23:12 > 0:23:15had been delivered the day before the murder
0:23:15 > 0:23:18to an upholstery company in Manhattan,
0:23:18 > 0:23:21run by Theodore Kruger.
0:23:21 > 0:23:23It was alibi time.
0:23:28 > 0:23:32Theodore Kruger said he'd been in his own premises all morning,
0:23:32 > 0:23:35with witnesses to prove it.
0:23:35 > 0:23:38But John Fiorenza claimed he'd been at an office,
0:23:38 > 0:23:40which the police soon found out
0:23:40 > 0:23:43had been closed on the day of the murder.
0:23:45 > 0:23:47They brought him in for questioning
0:23:47 > 0:23:51and after having a bit of fun with his impossible alibi,
0:23:51 > 0:23:54one of the detectives simply laid the piece of cord
0:23:54 > 0:23:57down on the table in front of him.
0:23:57 > 0:23:59Fiorenza went silent.
0:24:00 > 0:24:04After a night in the cells, he confessed.
0:24:04 > 0:24:07On 9th April, the day before the murder,
0:24:07 > 0:24:10he'd gone with Theodore Kruger to collect the seat
0:24:10 > 0:24:13and had managed somehow, during this brief encounter,
0:24:13 > 0:24:18to persuade himself that Nancy Titterton was attracted to him.
0:24:18 > 0:24:22The following morning, he'd gone back to see if he was right,
0:24:22 > 0:24:25with a coil of twine in his pocket in case he wasn't.
0:24:30 > 0:24:33The NYPD were justly proud.
0:24:33 > 0:24:36They paraded John Fiorenza for the cameras -
0:24:36 > 0:24:39white fedora, cigarette in mouth,
0:24:39 > 0:24:41headed for the electric chair.
0:24:43 > 0:24:46He'd raped and strangled Nancy Titterton
0:24:46 > 0:24:49and the NYPD had proved it.
0:24:50 > 0:24:53It had taken them just ten days.
0:24:57 > 0:25:00The moral of the story was simple.
0:25:00 > 0:25:05All investigating officers anywhere in the world needed to do
0:25:05 > 0:25:09was do what had been done in Manhattan in 1936 -
0:25:09 > 0:25:10use science.
0:25:10 > 0:25:15Preserve and analyse the crime scene in microscopic detail
0:25:15 > 0:25:17and act on the evidence generated.
0:25:21 > 0:25:24By the middle years of the 20th century,
0:25:24 > 0:25:27faith in forensic science was limitless.
0:25:27 > 0:25:30It seemed there was no crime it couldn't solve.
0:25:31 > 0:25:36Some crime scientists would become personally famous.
0:25:36 > 0:25:40The American Paul Leland Kirk was one of the most famous of all.
0:25:42 > 0:25:46As he wrote in his book, Crime Investigation,
0:25:46 > 0:25:48physical evidence cannot be wrong.
0:25:49 > 0:25:51It cannot perjure itself.
0:25:51 > 0:25:53It cannot be wholly absent.
0:25:55 > 0:25:58Only human failure to find it,
0:25:58 > 0:26:00study and understand it,
0:26:00 > 0:26:01can diminish its value.
0:26:06 > 0:26:09It sounds like an astonishingly confident statement
0:26:09 > 0:26:12on the power of forensic science -
0:26:12 > 0:26:16and yet, there's that last sentence with its emphasis on human failing.
0:26:17 > 0:26:20Paul Kirk wrote those words in 1953
0:26:20 > 0:26:24and it's almost as if he knew what would happen next -
0:26:24 > 0:26:28knew that he was about to become involved in a case
0:26:28 > 0:26:31where the simple rules - the basic procedures -
0:26:31 > 0:26:35would be forgotten, abused, ignored.
0:26:47 > 0:26:51On January 22nd 1955,
0:26:51 > 0:26:55Paul Kirk arrived in the small town of Bay Village,
0:26:55 > 0:26:59near Cleveland, Ohio, on the shores of Lake Erie.
0:27:04 > 0:27:08He was America's most revered forensic scientist,
0:27:08 > 0:27:12come all the way from California to analyse a crime scene,
0:27:12 > 0:27:14but it was a cold case
0:27:14 > 0:27:19and Dr Kirk was more than six months too late.
0:27:19 > 0:27:23The crime had taken place on July 4th of the previous year,
0:27:23 > 0:27:28and Kirk was here to help the defence lawyers prepare an appeal.
0:27:30 > 0:27:32Their client was already in jail,
0:27:32 > 0:27:35convicted of second degree murder.
0:27:35 > 0:27:38The victim, as usual, was a woman.
0:27:38 > 0:27:40Her name was Marilyn Sheppard
0:27:40 > 0:27:42and the convicted killer was her husband Sam.
0:27:44 > 0:27:47She'd been beaten to death in her bedroom...
0:27:48 > 0:27:51..and this was the room that Kirk had come to see.
0:28:01 > 0:28:05Those black spots, those splashes,
0:28:05 > 0:28:08are blood - all blood.
0:28:08 > 0:28:12All four walls were spotted and splashed with blood.
0:28:16 > 0:28:18This is the bed,
0:28:18 > 0:28:20once her body had been removed.
0:28:27 > 0:28:29Until that day,
0:28:29 > 0:28:34the Sheppards had seemed to be the ideal American couple -
0:28:34 > 0:28:39college sweethearts, happy, wholesome, prosperous.
0:28:41 > 0:28:45Dr Sheppard was a surgeon at the local hospital -
0:28:45 > 0:28:47a business that his family owned -
0:28:47 > 0:28:49and at the time of her death,
0:28:49 > 0:28:52Marilyn had been four months pregnant with their second child.
0:28:54 > 0:28:58But at the trial, the prosecution had revealed that Sam Sheppard had
0:28:58 > 0:29:00had an affair two years before.
0:29:03 > 0:29:07The happy marriage, it seemed, was an illusion.
0:29:07 > 0:29:10So this was the story the jury chose to believe.
0:29:17 > 0:29:22In their luxurious lakeside house on 3rd July 1954,
0:29:22 > 0:29:25the Sheppards had friends round for dinner.
0:29:25 > 0:29:27They watched a film.
0:29:27 > 0:29:29Marilyn sat on Sam's lap.
0:29:31 > 0:29:34Later, Sam fell asleep on a day bed
0:29:34 > 0:29:38at the bottom of the stairs that led up to their bedroom.
0:29:38 > 0:29:42Their guests left and sometime in the early hours of the morning,
0:29:42 > 0:29:47Sam woke up, went upstairs to where his wife was sleeping
0:29:47 > 0:29:51and beat her to death, leaving her body in her bed...
0:29:53 > 0:29:55..fractured skull,
0:29:55 > 0:29:58broken and missing teeth,
0:29:58 > 0:30:00mattress soaked with blood and urine.
0:30:05 > 0:30:07Sam Sheppard's version was different.
0:30:09 > 0:30:13He said that he'd been woken from his deep sleep on the day bed
0:30:13 > 0:30:15by strange, loud noises.
0:30:18 > 0:30:21He'd gone upstairs to find someone in their bedroom -
0:30:21 > 0:30:24someone who'd knocked him unconscious.
0:30:24 > 0:30:26When he came to, he discovered
0:30:26 > 0:30:29Marilyn lying on the bed, soaked in blood.
0:30:29 > 0:30:32He knelt beside her to see if she was breathing
0:30:32 > 0:30:36and at this point, he heard noises coming from the floor below.
0:30:36 > 0:30:38Rushing downstairs,
0:30:38 > 0:30:42he was just in time to see someone leaving through the back door.
0:30:44 > 0:30:46From the back of the house,
0:30:46 > 0:30:51a set of stairs led all the way down to the shore of Lake Erie.
0:30:51 > 0:30:55Sam chased this figure down the stairs to the lake,
0:30:55 > 0:30:56where they struggled
0:30:56 > 0:31:01and Sam Sheppard was once again knocked unconscious.
0:31:02 > 0:31:06When he awoke, he was lying partly in the water.
0:31:06 > 0:31:10His trousers were soaked and his T-shirt had been stolen.
0:31:10 > 0:31:14He returned to the house and at around five in the morning
0:31:14 > 0:31:18he called not the police, but his neighbours,
0:31:18 > 0:31:21telling them "Come quick, I think they've killed Marilyn."
0:31:24 > 0:31:27The jury weren't convinced.
0:31:30 > 0:31:32Now, nearly seven months later,
0:31:32 > 0:31:35Sam Sheppard was in jail.
0:31:35 > 0:31:38All that stood between him and a life sentence
0:31:38 > 0:31:41was Dr Paul Kirk.
0:31:41 > 0:31:44In the bedroom where Marilyn had died,
0:31:44 > 0:31:49Kirk set about the painstaking task of rebuilding the crime scene.
0:31:49 > 0:31:53The bloodstained walls and doors were still there,
0:31:53 > 0:31:56still smeared with fingerprint powder.
0:31:56 > 0:31:59He had obtained the sheets, the pillowcases,
0:31:59 > 0:32:01the mattresses of both beds.
0:32:03 > 0:32:05He proceeded carefully...
0:32:07 > 0:32:09..measured everything...
0:32:12 > 0:32:15..referred constantly to the original crime scene pictures.
0:32:18 > 0:32:21He was here to see if he could make sense of it all.
0:32:23 > 0:32:26Were there signs of the intruder?
0:32:26 > 0:32:31Or signs only of a husband's fatal assault on his wife?
0:32:33 > 0:32:37But there must have been another question in Paul Kirk's mind
0:32:37 > 0:32:40as he stood here, studying these photographs
0:32:40 > 0:32:45with their spattered walls and horribly bloodstained sheets.
0:32:45 > 0:32:49Why was it only now, more than six months after the murder,
0:32:49 > 0:32:53that a crime scene analyst of his skill and experience
0:32:53 > 0:32:56was standing here where Marilyn had died?
0:32:56 > 0:32:58Why hadn't this been done before?
0:33:01 > 0:33:03It looked as though it had.
0:33:04 > 0:33:06The original crime scene photographer
0:33:06 > 0:33:08had certainly worked hard.
0:33:11 > 0:33:13But most of what he recorded -
0:33:13 > 0:33:17Sam Sheppard's medical bag overturned,
0:33:17 > 0:33:20signs of disturbance in several other rooms,
0:33:20 > 0:33:24drawers pulled out and their contents dumped -
0:33:24 > 0:33:26was never really analysed at all.
0:33:30 > 0:33:32Bay Village was in Cuyahoga County.
0:33:34 > 0:33:38It had its own small police force and its own county coroner.
0:33:42 > 0:33:46It would have been very simple for that coroner, Dr Samuel Gerber,
0:33:46 > 0:33:51to call the nearby city of Cleveland and ask for crime scene analysts,
0:33:51 > 0:33:53but he didn't.
0:33:55 > 0:33:58From the moment he arrived at the Sheppard house,
0:33:58 > 0:34:02Gerber was certain that Sam Sheppard was guilty.
0:34:02 > 0:34:06He never entertained any other possibility
0:34:06 > 0:34:07and under his control,
0:34:07 > 0:34:12the investigation unfolded as a catalogue of errors.
0:34:12 > 0:34:15The crime scene was not properly secured.
0:34:16 > 0:34:20Journalists were allowed access on the day of the discovery.
0:34:21 > 0:34:24Sam Sheppard had injuries to the back of his neck.
0:34:25 > 0:34:28Self-inflicted, or the work of the intruder?
0:34:29 > 0:34:31Gerber never bothered to study them.
0:34:35 > 0:34:37The room was covered in blood,
0:34:37 > 0:34:39but Gerber would ignore it all,
0:34:39 > 0:34:43except for the stains on Marilyn's pillow,
0:34:43 > 0:34:48in which Gerber thought he could see the outline of a medical instrument.
0:34:50 > 0:34:53He became convinced that Sheppard had killed his wife
0:34:53 > 0:34:56with one of the tools of his trade.
0:34:56 > 0:35:00He wasted months in the search for a weapon that matched the stain.
0:35:03 > 0:35:05But worst of all,
0:35:05 > 0:35:08that search for something that fitted the mysterious outline
0:35:08 > 0:35:14was the only analysis he ever conducted of the spatters and stains
0:35:14 > 0:35:17that covered the walls and beds.
0:35:17 > 0:35:20All of it was evidence and it was all ignored.
0:35:24 > 0:35:29Paul Kirk would focus on precisely what Gerber had neglected -
0:35:29 > 0:35:31the patterns of bloodstaining -
0:35:31 > 0:35:34and he had noticed something significant.
0:35:37 > 0:35:39All four walls had blood on,
0:35:39 > 0:35:41but as his diagram shows,
0:35:41 > 0:35:44in what he called the north-east corner,
0:35:44 > 0:35:46he found no blood at all.
0:35:47 > 0:35:50A blood void.
0:35:50 > 0:35:52Why was there no blood there?
0:35:57 > 0:36:00'At Harperley Hall Police Training College near Durham,
0:36:00 > 0:36:04'there are facilities for training in blood pattern analysis.'
0:36:05 > 0:36:08If you only had three drops and I really hit it like that,
0:36:08 > 0:36:09it's going to break it up....
0:36:09 > 0:36:12- 'That's what Pete Smith teaches...' - If you then apply the same....
0:36:12 > 0:36:15'..and he's going to show me what a blood void is -
0:36:15 > 0:36:17'and what it means.'
0:36:17 > 0:36:19..Keep my mouth shut for this one.
0:36:19 > 0:36:23Right, so I'm going to...probably use that amount of blood.
0:36:23 > 0:36:25'In the corner of the training room,
0:36:25 > 0:36:28'Pete puts horse blood in the palm of his hand...'
0:36:28 > 0:36:29One, two, three.
0:36:29 > 0:36:33'..and punches it several times to create spatter across the walls.'
0:36:35 > 0:36:37One, two, three.
0:36:38 > 0:36:40Like that, OK? So, one punch.
0:36:40 > 0:36:42Spread it onto my upper front here
0:36:42 > 0:36:44and if you look over my left shoulder,
0:36:44 > 0:36:47you can see a lot of spatter. This is called impact spatter,
0:36:47 > 0:36:50that's been projected from the punch, up onto the wall
0:36:50 > 0:36:52and indeed, onto the ceiling.
0:36:52 > 0:36:54And if I actually move away, you can see that
0:36:54 > 0:36:57there's actually what we call a "void area" on the wall...
0:36:57 > 0:37:00- Yes.- ..which I think most people would equate with
0:37:00 > 0:37:03the position of my body at the time of the beating.
0:37:05 > 0:37:08'Here was strong evidence that Marilyn's killer
0:37:08 > 0:37:11'had stood on the right-hand side of her bed,
0:37:11 > 0:37:12'in the blood void.
0:37:14 > 0:37:17'Now, Paul Kirk wanted to try and understand
0:37:17 > 0:37:20'the patterns of blood spatter themselves.
0:37:22 > 0:37:26'He soaked a sponge rubber pad with blood
0:37:26 > 0:37:28'and struck it in different ways,
0:37:28 > 0:37:30'from different angles,
0:37:30 > 0:37:32'with different weapons.'
0:37:35 > 0:37:38So I'm just going to load some blood, using the pipette,
0:37:38 > 0:37:39onto the surface here.
0:37:39 > 0:37:41Just a little bit more....
0:37:41 > 0:37:43'Pete Smith uses a joint of pork.'
0:37:46 > 0:37:48So, after three -
0:37:48 > 0:37:50one, two, three.
0:37:54 > 0:37:55- That's good.- Wow.
0:37:57 > 0:38:00'I'm used to blood, but not to violence.'
0:38:02 > 0:38:04Feels horrible, I have to say.
0:38:04 > 0:38:06It depends how many times you've done it.
0:38:09 > 0:38:11One, two, three.
0:38:14 > 0:38:15Excellent.
0:38:18 > 0:38:20'Different actions make different spatter.'
0:38:21 > 0:38:24In the photographs from the bedroom,
0:38:24 > 0:38:27Paul Kirk had observed that the largest drops of blood
0:38:27 > 0:38:30were on the bedroom and wardrobe doors,
0:38:30 > 0:38:32both on Marilyn's right.
0:38:35 > 0:38:39In his experiments, he found that these large drops
0:38:39 > 0:38:43were usually associated with "cast off", or "throw off" -
0:38:43 > 0:38:46blood that had accumulated on the weapon
0:38:46 > 0:38:49and was thrown off as it was raised to strike.
0:38:52 > 0:38:56The blood drops on Sam's bed, to her left, were much smaller.
0:38:58 > 0:39:02These were blood drops produced by the impact of the weapon.
0:39:05 > 0:39:08So this, Paul Kirk concluded,
0:39:08 > 0:39:10was the arc the weapon had been swung through.
0:39:13 > 0:39:16He was more and more certain
0:39:16 > 0:39:20that Marilyn had been struck by a man standing on her right,
0:39:20 > 0:39:23holding the weapon in his left hand.
0:39:24 > 0:39:27Sam Sheppard was a right-handed man.
0:39:33 > 0:39:36What do you say about the possibility from blood spatter
0:39:36 > 0:39:39of being able to determine something
0:39:39 > 0:39:43like whether an assailant was left-handed or right-handed?
0:39:43 > 0:39:46I personally would exercise some degree of caution,
0:39:46 > 0:39:49because you could have somebody who's right-handed
0:39:49 > 0:39:52swinging from here to here,
0:39:52 > 0:39:54or they could swing from left to right
0:39:54 > 0:39:56and similarly, with a person who's left-handed,
0:39:56 > 0:39:58left to right or right to left.
0:39:58 > 0:40:00It's all about observing,
0:40:00 > 0:40:02inferring something from what you see
0:40:02 > 0:40:04and then passing your opinion.
0:40:04 > 0:40:07Somebody else can always have a different opinion.
0:40:11 > 0:40:15Blood pattern analysis has been practised for decades
0:40:15 > 0:40:19and these days, professionals like Pete Smith have become aware
0:40:19 > 0:40:23that what they can offer is at best an interpretation -
0:40:23 > 0:40:25a probability.
0:40:25 > 0:40:29But Paul Kirk believed he could be very definite
0:40:29 > 0:40:32and after two months of experiments,
0:40:32 > 0:40:36he presented a detailed report to Sam Sheppard's defence lawyers.
0:40:39 > 0:40:43His conclusions were very powerful.
0:40:43 > 0:40:46He excluded Sam Sheppard from the scene of death,
0:40:46 > 0:40:48apart from as a distressed husband.
0:40:48 > 0:40:51He put great emphasis on his belief
0:40:51 > 0:40:53that the killer was a left-handed man.
0:41:02 > 0:41:03Ten years passed
0:41:03 > 0:41:07while Sheppard's lawyers struggled to obtain a retrial,
0:41:07 > 0:41:10so it wasn't until 1966
0:41:10 > 0:41:14that Paul Kirk finally went on the stand to present his evidence.
0:41:17 > 0:41:21When he did, the prosecution had nothing to rebut
0:41:21 > 0:41:25his analysis of the spatter patterns.
0:41:25 > 0:41:29Sam Sheppard was acquitted and left court a free man...
0:41:30 > 0:41:32..but a broken one.
0:41:32 > 0:41:35He died of liver failure in 1970.
0:41:38 > 0:41:40Was he innocent?
0:41:40 > 0:41:43Did he struggle with an intruder by Lake Erie,
0:41:43 > 0:41:46or did he beat his pregnant wife to death?
0:41:47 > 0:41:49It's impossible to say.
0:41:50 > 0:41:55The original investigation left too much evidence untouched,
0:41:55 > 0:42:00and some people have always felt that the jury at the retrial
0:42:00 > 0:42:04were blinded by Paul Kirk's scientific authority.
0:42:07 > 0:42:11What we can say with absolute certainty is this -
0:42:11 > 0:42:15without Paul Kirk's evidence, without his analysis,
0:42:15 > 0:42:19Sam Sheppard would have died in jail.
0:42:19 > 0:42:22Forensic science had secured his freedom.
0:42:26 > 0:42:28The Sheppard case reminds us
0:42:28 > 0:42:31that there are two kinds of forensic science.
0:42:34 > 0:42:37Some is definitely science -
0:42:37 > 0:42:39Georg Popp's analysis of soil.
0:42:40 > 0:42:45The NYPD's careful scrutiny of an apparently ordinary cord.
0:42:46 > 0:42:49But some, like Paul Kirk's investigation,
0:42:49 > 0:42:54is really about opinion and interpretation -
0:42:54 > 0:42:56and without proper safeguards,
0:42:56 > 0:42:59it can borrow the authority of science
0:42:59 > 0:43:03and disguise those opinions as hard, scientific fact.
0:43:04 > 0:43:09It's a particular risk for a kind of crime scene evidence
0:43:09 > 0:43:12that we've sworn by for more than a century.
0:43:15 > 0:43:17We leave them everywhere we go.
0:43:17 > 0:43:21We can't help it - unless we're wearing gloves, of course.
0:43:21 > 0:43:22Fingerprints.
0:43:22 > 0:43:26They're one of the oldest forms of crime scene evidence we have.
0:43:26 > 0:43:28We trust them implicitly.
0:43:28 > 0:43:32The idea that everybody has different, unique fingerprints
0:43:32 > 0:43:34is an article of faith.
0:43:36 > 0:43:40The gold standard of crime scene evidence.
0:43:40 > 0:43:42Incontrovertible proof
0:43:42 > 0:43:46that the suspect had been exactly where they said they hadn't.
0:43:48 > 0:43:51But a little more than 100 years ago,
0:43:51 > 0:43:53things were completely different.
0:43:57 > 0:43:59On 2nd May 1905,
0:43:59 > 0:44:03prosecuting counsel Richard Muir arrived at the Old Bailey.
0:44:04 > 0:44:08He had just two days in court to convict two men.
0:44:09 > 0:44:14The only evidence of their presence at the crime scene was a fingerprint
0:44:14 > 0:44:19and the idea that fingerprints were unique to each person was new.
0:44:20 > 0:44:24His fingerprint evidence was itself on trial.
0:44:26 > 0:44:31The crime had taken place at number 34 Deptford High Street,
0:44:31 > 0:44:34where Thomas and Ann Farrow, an elderly couple,
0:44:34 > 0:44:37managed a shop selling inks and paints.
0:44:42 > 0:44:46Two men had gained entry to the shop and attacked the Farrows.
0:44:50 > 0:44:52Thomas died on the scene,
0:44:52 > 0:44:55Ann from her injuries a few days later.
0:44:56 > 0:44:59The thieves, Alfred and Albert Stratton,
0:44:59 > 0:45:02found the shop's cashbox in the bedroom.
0:45:06 > 0:45:10It contained about £13.
0:45:10 > 0:45:12The Strattons must have been hoping for more,
0:45:12 > 0:45:15but they took the money and fled,
0:45:15 > 0:45:18sure that their masks had protected their identities.
0:45:21 > 0:45:24In fact, they should have been wearing gloves.
0:45:27 > 0:45:30In 1905, there was absolutely no reason
0:45:30 > 0:45:33why two amateurs like the Stratton brothers
0:45:33 > 0:45:37would have known that their own hands could give them away.
0:45:37 > 0:45:42Scotland Yard's Fingerprint Bureau had only been founded in 1901
0:45:42 > 0:45:45and fingerprint evidence had only ever been used
0:45:45 > 0:45:48in a low profile burglary case,
0:45:48 > 0:45:51so the Strattons hadn't worn gloves
0:45:51 > 0:45:55and that's why they left behind a crucial piece of evidence.
0:45:57 > 0:45:59A thumbprint, in fact.
0:45:59 > 0:46:02The Fingerprint Bureau were certain it had been left
0:46:02 > 0:46:05by one of their leading suspects, the Stratton brothers.
0:46:08 > 0:46:12They were sure they had a match with Alfred Stratton's right thumb
0:46:12 > 0:46:16and there was no innocent reason for that thumbprint to be there.
0:46:16 > 0:46:19As long as you accepted the newfangled idea
0:46:19 > 0:46:21that fingerprints were unique,
0:46:21 > 0:46:23then it proved his presence
0:46:23 > 0:46:27and his criminal intent at the scene of the crime.
0:46:31 > 0:46:34But what if you didn't accept that idea?
0:46:34 > 0:46:38Muir had to defend his fingerprint evidence.
0:46:38 > 0:46:41Over 40 eyewitnesses had seen the Strattons
0:46:41 > 0:46:44near the shop on that morning.
0:46:44 > 0:46:47Muir called them all to the witness stand.
0:46:49 > 0:46:52He must have rehearsed them all for speed.
0:46:52 > 0:46:57He had to allow as much time as possible for his expert witness,
0:46:57 > 0:47:02Detective Inspector Charles Collins of the Fingerprint Bureau,
0:47:02 > 0:47:04because when Collins took the stand,
0:47:04 > 0:47:07he couldn't just say he'd found a thumbprint
0:47:07 > 0:47:10and it belonged to Alfred Stratton.
0:47:10 > 0:47:13He would first have to explain to the jury
0:47:13 > 0:47:14what fingerprints were
0:47:14 > 0:47:17and why they were proof of anything at all.
0:47:23 > 0:47:27'We don't have to travel back in time to hear what Collins said.
0:47:28 > 0:47:32'The methods of fingerprinting haven't changed at all.'
0:47:33 > 0:47:35The most important thing is not to be rushed...
0:47:35 > 0:47:39'Stephen Hughes is a fingerprint analyst
0:47:39 > 0:47:41'of over 30 years' experience.'
0:47:41 > 0:47:45So, Stephen - talk me through some of the basic principles.
0:47:45 > 0:47:47When we make an identification,
0:47:47 > 0:47:50there are two levels of identification we have to make.
0:47:50 > 0:47:54The first level of detail is the patterns.
0:47:54 > 0:47:56Now, as you can see here,
0:47:56 > 0:47:58there are three basic patterns.
0:47:59 > 0:48:01That is the arch type pattern,
0:48:01 > 0:48:04which is fairly clear to see why it's called an arch type pattern.
0:48:06 > 0:48:08You have a loop type pattern...
0:48:11 > 0:48:13..and you have the whorl.
0:48:14 > 0:48:17And then we take it to the next level.
0:48:17 > 0:48:19Fingerprints are formed by ridges.
0:48:21 > 0:48:25These ridges are the black lines you see on these patterns
0:48:25 > 0:48:28and at the summit of these ridges are microscopic pores.
0:48:28 > 0:48:31The microscopic pores exude sweat.
0:48:31 > 0:48:34The sweat runs along the ridges and then,
0:48:34 > 0:48:37when we place our hand and grasp something,
0:48:37 > 0:48:42we find an image of the ridge detail upon it in sweat
0:48:42 > 0:48:44and that's a latent fingerprint.
0:48:44 > 0:48:47The ridges will suddenly end
0:48:47 > 0:48:50or bifurcate into two, like here.
0:48:51 > 0:48:53This is what makes us individuals.
0:48:54 > 0:48:59What would be the smallest percentage of a print
0:48:59 > 0:49:03on which you would be able to confidently make an identification?
0:49:04 > 0:49:08I would like to have at least nine or ten ridge characteristics
0:49:08 > 0:49:12in coincident sequence, without any in disagreement.
0:49:15 > 0:49:17So, Stephen's looking for nine or ten places
0:49:17 > 0:49:22where ridge lines break or split in two
0:49:22 > 0:49:26in exactly the same way in both the crime scene mark
0:49:26 > 0:49:29and the fingerprint taken by the police.
0:49:29 > 0:49:33He could find what he needs in an area this small.
0:49:34 > 0:49:36In 1905,
0:49:36 > 0:49:39DI Collins had worked in the same way.
0:49:39 > 0:49:41In the courtroom,
0:49:41 > 0:49:46he gave the jury and the Stratton brothers a whistle-stop tour
0:49:46 > 0:49:50through these basic principles of fingerprint analysis.
0:49:53 > 0:49:57At last, he produced two images -
0:49:57 > 0:50:00an enlargement of the mark taken from the cashbox
0:50:00 > 0:50:02and an enlargement of the print
0:50:02 > 0:50:05taken from Alfred Stratton's right thumb.
0:50:06 > 0:50:10And he drew the court's attention, one by one,
0:50:10 > 0:50:13to 11 ridge details at which the prints agreed.
0:50:16 > 0:50:19"This is definitely the fingerprint of Alfred Stratton",
0:50:19 > 0:50:21DI Collins insisted.
0:50:23 > 0:50:26Muir had made his case.
0:50:26 > 0:50:29Now, he would have to watch as the defence attacked
0:50:29 > 0:50:33the very idea of fingerprint evidence.
0:50:35 > 0:50:38First, they called Dr John George Garson,
0:50:38 > 0:50:43a man who knew contemporary police practices well,
0:50:43 > 0:50:47but had only a passing knowledge of the principles of fingerprinting.
0:50:48 > 0:50:50But the jury didn't know that
0:50:50 > 0:50:52and he certainly looked convincing
0:50:52 > 0:50:56as he conducted a point-by-point rebuttal of Collins' evidence.
0:51:00 > 0:51:04Garson said fingerprints proved nothing at all,
0:51:04 > 0:51:07but when Richard Muir took over to cross-examine,
0:51:07 > 0:51:10he stopped Garson in his tracks.
0:51:10 > 0:51:12He produced a letter,
0:51:12 > 0:51:16in which Garson had offered to testify for the prosecution.
0:51:17 > 0:51:21He would give evidence for whoever paid him most.
0:51:21 > 0:51:25The judge told the jury to ignore his evidence.
0:51:27 > 0:51:29The defence were so horrified
0:51:29 > 0:51:33that they decided not to call their second expert at all,
0:51:33 > 0:51:36which, for Richard Muir and the prosecution,
0:51:36 > 0:51:39was the very best thing that could have happened.
0:51:40 > 0:51:44They would have had trouble with the questions this expert witness
0:51:44 > 0:51:46never got a chance to ask.
0:51:47 > 0:51:53He thought all ten fingerprints were needed to prove unique identity -
0:51:53 > 0:51:55and as for the crime scene finger mark,
0:51:55 > 0:51:59the result of a brief contact or a glancing touch....
0:52:01 > 0:52:04How good could such an image possibly be?
0:52:09 > 0:52:12That unasked question has recently come back
0:52:12 > 0:52:15to haunt the field of fingerprint evidence.
0:52:20 > 0:52:26In 1997, Detective Constable Shirley McKie of Strathclyde Police
0:52:26 > 0:52:29was working on a murder case in Kilmarnock.
0:52:30 > 0:52:34The fatal stabbing of Marion Ross, aged 51.
0:52:39 > 0:52:43A print was found on the bathroom doorpost inside the house.
0:52:46 > 0:52:49It was logged as "Fingerprint Y7",
0:52:49 > 0:52:52and identified by fingerprint analysts
0:52:52 > 0:52:54as the left thumbprint of Shirley McKie.
0:52:58 > 0:53:02But her duties had never required her to enter the house.
0:53:02 > 0:53:06It was a serious breach of protocol if she had.
0:53:08 > 0:53:12Shirley McKie insisted that she hadn't been inside the house
0:53:12 > 0:53:16and Strathclyde Police were now faced with an interesting decision.
0:53:16 > 0:53:19Did they trust in the science of fingerprints,
0:53:19 > 0:53:22or did they trust Detective Constable McKie?
0:53:22 > 0:53:24It wasn't a difficult decision.
0:53:24 > 0:53:26They chose fingerprints.
0:53:30 > 0:53:35Shirley McKie would be charged with perjury and lose her job.
0:53:40 > 0:53:44But fast forward to 2011.
0:53:44 > 0:53:46Shirley McKie isn't on trial.
0:53:48 > 0:53:51Fingerprint evidence is,
0:53:51 > 0:53:52and this is the verdict.
0:53:54 > 0:53:59One - there is no evidence other than the mark Y7
0:53:59 > 0:54:01to suggest Miss McKie at any time
0:54:01 > 0:54:06entered Miss Ross's house beyond the area of the porch.
0:54:07 > 0:54:13Two - the mark Y7 on the doorframe of the bathroom in Miss Ross's house
0:54:13 > 0:54:18was misidentified as the fingerprint of Miss McKie.
0:54:19 > 0:54:23Three - Miss McKie did not make the mark Y7.
0:54:26 > 0:54:29It had taken 14 years,
0:54:29 > 0:54:32but here, at last, was clarity.
0:54:32 > 0:54:35Shirley McKie had told the truth.
0:54:35 > 0:54:40The fingerprint analysts, who said the mark Y7 was hers, were wrong.
0:54:45 > 0:54:49You can trace that case back to a Scottish judgment,
0:54:49 > 0:54:53a Scottish appeal court case, sometime in the '30s,
0:54:53 > 0:54:55where the judge described fingerprints as
0:54:55 > 0:54:57"practically infallible".
0:54:57 > 0:55:00It's a very curious phrase
0:55:00 > 0:55:02and it's certainly my impression
0:55:02 > 0:55:05that as a consequence of that,
0:55:05 > 0:55:07that notion of infallibility...
0:55:07 > 0:55:09Gradually, that idea took hold.
0:55:09 > 0:55:13That then became evidence that was essentially incontestable.
0:55:14 > 0:55:16It was error-free.
0:55:16 > 0:55:19It didn't merit any kind of argument or challenge,
0:55:19 > 0:55:23and it became a matter of routine.
0:55:23 > 0:55:26So, it became embedded as a presumption
0:55:26 > 0:55:28in the legal process in Scotland,
0:55:28 > 0:55:31that fingerprints were simply incontrovertible evidence.
0:55:34 > 0:55:37Not just in Scotland, of course.
0:55:38 > 0:55:41There were other cases in other countries
0:55:41 > 0:55:43where fingerprints were misidentified.
0:55:44 > 0:55:48The errors were always human.
0:55:50 > 0:55:55The cases where we have seen mistakes are often to do with
0:55:55 > 0:55:57particular situations in the case,
0:55:57 > 0:56:01and it is usually one or two things in combination.
0:56:01 > 0:56:05The first one is often that it's a difficult mark, a complex mark.
0:56:05 > 0:56:08In other words, a finger mark that might have been twisted or distorted
0:56:08 > 0:56:12or laid on an unusual surface that affected it.
0:56:12 > 0:56:16And the second one is that they tend to be in very high profile cases.
0:56:20 > 0:56:22The McKie case was typical.
0:56:23 > 0:56:26The crime scene mark was complex.
0:56:26 > 0:56:29Two fingerprints overlapped each other...
0:56:30 > 0:56:33..and the investigators were under pressure,
0:56:33 > 0:56:36surrounded by intense media interest.
0:56:39 > 0:56:41Under these circumstances,
0:56:41 > 0:56:45analysts can start to see what they expect or hope to see,
0:56:45 > 0:56:47not what's really there.
0:56:49 > 0:56:51It isn't very scientific,
0:56:51 > 0:56:53but it is entirely human.
0:57:00 > 0:57:02In 1905,
0:57:02 > 0:57:06Detective Inspector Collins made his match
0:57:06 > 0:57:08and went unchallenged -
0:57:08 > 0:57:12and no analyst has ever suggested since
0:57:12 > 0:57:15that the fingerprint evidence in the Stratton brothers case
0:57:15 > 0:57:19was anything other than a decent fit.
0:57:22 > 0:57:26The Stratton brothers were executed in Wandsworth
0:57:26 > 0:57:30at 9am on 23rd May, 1905.
0:57:32 > 0:57:35It was the first murder case in a British court
0:57:35 > 0:57:39in which fingerprint evidence had helped secure a conviction.
0:57:43 > 0:57:45There's no doubt at all.
0:57:45 > 0:57:50We've seen it for ourselves that science continues to deliver
0:57:50 > 0:57:53new techniques for the capture of evidence.
0:57:53 > 0:57:58But machines and chemical tests don't interpret evidence.
0:57:58 > 0:57:59People do -
0:57:59 > 0:58:00and they can get it wrong.
0:58:04 > 0:58:08Next time, I'll reveal why the murder weapon
0:58:08 > 0:58:12is such a vital piece of evidence.
0:58:12 > 0:58:14Firearms,
0:58:14 > 0:58:15poisons,
0:58:15 > 0:58:17knives...
0:58:17 > 0:58:22Weapons can hold all the clues needed to catch a killer.
0:58:23 > 0:58:26Delve deeper with the Open University
0:58:26 > 0:58:30and find out more about the science behind forensics.
0:58:30 > 0:58:33Go to:
0:58:35 > 0:58:37..and follow the links to the Open University.