Forensics

by Val McDermid

  To understand the pros and cons of genetic fingerprinting we need to revisit the first crime it helped to solve, in the tranquil and ancient village of Narborough in Leicestershire. On 22 November 1983, the body of 15-year-old Lynda Mann was found strangled and raped near a footpath. She was naked from the waist down and her face was bloodied. Biologists established that a semen sample taken from her body belonged to someone with Type A blood, and a particular type of enzyme secretion, a combination shared by only 10 per cent of men. But with little else to go on, the case went cold.

  Three years later, on 31 July 1986, Dawn Ashworth, also aged fifteen, went missing. Her body was found near to Lynda’s, just off Ten Pound Lane. Again, she had been strangled, raped and left naked from the waist down.

  The main suspect was Richard Buckland, a 17-year-old hospital porter with learning disabilities. Buckland had a troubled past and had been spotted near the scene of the crime. When interviewed, he revealed details about Dawn’s murder, and about her body, that weren’t publicly available. Before long he confessed to her murder. But he vehemently denied killing Lynda three years earlier.

  Convinced that the same man had murdered both girls, police approached Alec Jeffreys at the University of Leicester, five miles from Narborough, who had recently appeared in a local news story about ‘genetic fingerprints’. His analysis of the semen samples revealed that the police were right: the same man had committed both murders, but he was not Richard Buckland. Despite his confession, Buckland was exonerated – the first person to be proven innocent based on DNA evidence.

  The police now had the genetic fingerprint of the killer but they had lost their only suspect. They asked all 5,000 adult men in Narborough and the surrounding villages to volunteer blood or saliva samples. Of the 10 per cent with the particular blood type taken from Lynda and Dawn’s bodies, Jeffreys established full DNA profiles. This was a huge and unprecedented undertaking. But, six months and considerable expense later, there was still no match, and again the case went cold.

  The following year, a woman sitting in a local pub overheard a local man called Ian Kelly boasting to friends that he had made £200 by posing as his mate, Colin Pitchfork, at the sampling. Pitchfork, a cake decorator – quiet but prone to bouts of temper – had asked Kelly, a colleague at the bakery where they worked, to take the DNA test for him. He said he’d been charged with indecent exposure in the past and wanted to avoid being harassed by the police. The excuse was shaky but £200 was cash enough to stop Kelly asking questions. The woman went to the police, who arrested Pitchfork and took his DNA. It matched. Finally, the detectives had their answer.

  In 1988 Pitchfork was sentenced to life imprisonment for both murders. Law enforcement agencies and scientists around the word sat up and took note. Gill Tully was an undergraduate biology student at Cardiff University at the time, and it took her breath away to see such a savage – and seemingly unsolvable – crime exposed by so sophisticated a scientific process. She finished her first degree and then went on to do a PhD at the Forensic Science Service, where she landed a job afterwards. There she was involved in some extraordinary developments at a time when the UK was the powerhouse for genetic research. Val Tomlinson had already been at the FSS for six years when Gill arrived, and she recalls the atmosphere of the pre-DNA days:

  ‘It was very hands-on. Personal protective equipment hadn’t really been invented. We rarely used gloves. One of the tests for semen staining was whether or not it was stiff to the touch. We didn’t have separate offices. Your bench was your office, so you wrote your reports on the same bench where you examined all your dirty knickers and bloodstained items.

  Colin Pitchfork, the first person in the UK to be convicted on the basis of DNA evidence

  ‘It is quite hilarious to think back about when we started DNA profiling. It was bucket chemistry, literally bucket chemistry, you would make whole vats of salt solutions and you had radioactive substances and you needed a bloodstain the size of a ten pence piece if not bigger to get a DNA profile.

  ‘In the early stages of my career there were no formal training courses other than a very initial one, and then you worked alongside an experienced scientist who took you along with them and you did everything from blood alcohol testing, semen staining, fibres analysis, hairs. I’ve done pheasant feather cases, I’ve done salmon poaching cases. I’ve done leek slashing cases.’

  When Gill arrived at the FSS during her sandwich year, while she was still an undergraduate at Cardiff, most of the geneticists approached their work with enthusiasm, but without taking much notice of the revolution they were setting in motion. ‘At coffee break the main issue was whether there was still a jam donut left,’ Gill says now with a rueful laugh. While the Colin Pitchfork case had shown the world how useful DNA could be, she admits, ‘We thought it would only be for those occasional really high-profile cases.’

  But over the years each innovation has broadened the application of DNA. ‘Every time you think, “Oh yes, that would be really good, it’s a bit too expensive for routine but that occasional high-profile crime, that could be the thing that makes a difference.” And yet a number of those have then become cheap enough and routine enough to use even in burglaries.’

  The most significant move away from ‘bucket chemistry’ was made by Kary Mullis, a Californian surfer and LSD enthusiast who went on to win the Nobel Prize in Chemistry. In 1983 Mullis was driving along Highway 128 when he had a revelation. If he added an enzyme called polymerase to DNA it would, in his words, ‘reproduce the hell out of itself’. Using the polymerase chain reaction (PCR), Mullis could take a very small amount of DNA and make it significant enough to interpret. Before long, scientists were using PCR to understand criminal cases that had been cold for up to seventy years, as well as the genealogy of fossilised dinosaurs and buried royalty, and the diagnosis of hereditary diseases.

  When Gill Tully started working at the FSS she and her supervisor were the only two people working on refining and using PCR; she regards herself as being ‘deeply privileged to have been there from the beginning’. Traditional genetic fingerprinting had relied on bodily fluids and hair, but by 1999 the team that Gill was part of was using PCR to develop a much more sensitive method, known as ‘low copy number (LCN) DNA profiling’. To get an LCN profile they needed only a few cells from a potential suspect. Whether it was a speck of dead skin, the sweat from a fingerprint or the dried saliva from a postage stamp, the required amount of bodily substance had spiralled down from the size of a ten pence piece to one millionth of a grain of salt.

  LCN profiling has had a seismic impact on the way crimes are investigated in the UK. But its road to acceptance has been a long one. Controversial trials involving LCN DNA evidence have provoked reactions from judges and commentators that have forced forensic geneticists to defend and redefine their methods.

  One particularly contentious trial that helped to shape the role of LCN DNA in court was triggered by a massive bomb in a small town in Northern Ireland. In 1998, the Good Friday Peace Agreement was reached, supposedly marking the end of hostilities between Unionist and Republican paramilitary organisations. But on 15 August the Real Irish Republican Army detonated a bomb which ripped through a busy street in Omagh, County Tyrone. Responding to a phoned-in warning from the bombers naming the local courthouse as the location, the police had actually moved people into the path of the blast, located in the centre of the town. Twenty-nine people were murdered, including several children and a pair of unborn twins. Over 200 were injured. The Secretary of State for Northern Ireland at the time, Mo Mowlam, described it as ‘mass murder’.

  Three years later, Colm Murphy, a building contractor, was convicted of causing the explosion and sentenced to fourteen years in prison. It was to be the start of a long and painfully unresolved judicial process. In 2005 his conviction was overturned when it emerged that police had forged notes of interviews they had conducted with him. The following year, the police arrested Colm Murphy’s
nephew, an electrician called Sean Hoey. At his trial the prosecution’s case rested on LCN DNA found on the bomb timers used in the attacks, which a forensic geneticist said was one billion times more likely to belong to Sean Hoey than to an unknown individual. But in the absence of eyewitness testimony, or any other compelling evidence, the case fell apart.

  When Mr Justice Weir delivered his judgment on 20 December 2007, he criticised the way the prosecution had made LCN DNA the crux of their case, rather than using it as a guide towards finding other substantial evidence. He complained about the ‘slapdash approach’ of the police and some forensic experts. He even alleged that the evidence had been ‘beefed up’ by police, who were guilty of ‘deliberate and calculated deception’ in their efforts to secure a conviction. He pointed out that the only published papers validating LCN DNA profiling were written by its inventors at the FSS. Ultimately Weir found the method too novel and recommended an urgent review of its use – a bad end to an investigation that cost the state £16 million.

  The day after Weir’s verdict the Crown Prosecution Service (CPS) suspended LCN DNA profiling, and commissioned a review of its fitness for purpose. Since 1999 it had been used in 21,000 serious crime cases in the UK and abroad – particularly in cold cases. The CPS ordered all live cases involving LCN DNA to be re-examined. One of them involved the brothers David and Terry Reed of Teesside in the north-east of England.

  On 12 October 2006 a friend of the former boxer and hard man Peter Hoe received a 4-minute-long voicemail message of the New Age music of Mike Oldfield. But when he played it back and listened carefully he could hear the muffled groans of Hoe, who was bleeding to death from five deep stab wounds in the living room of his house in Eston, near Middlesbrough. The police arrested and charged prime suspects David and Terry Reed. David, the older brother, was known to be jealous of Hoe’s tough reputation, and in court Hoe’s brother claimed that the attack was a retaliation for a pub scuffle some days earlier: ‘They went up to my brother’s house and murdered him because David couldn’t handle the hiding.’

  When Val examined Peter Hoe’s living room she found nothing to indicate that the perpetrators themselves had bled, but noticed two small pieces of plastic. ‘We see it all the time when knives are used in stabbings. The vibrations and forces project down the knife blade and hit the hilt with such force that it breaks.’ Back at the laboratory Val looked more closely at the plastic pieces and, based on her experience, decided they had originated from cheap knives. Traces of DNA were found on them. LCN profiling revealed that it matched the Reed brothers’.

  At the trial the defence called an eminent professor of plastics, ‘a lovely gentleman from Newcastle University’, who had been to Argos and bought a cheap knife with a plastic handle. Then he had put the knife into a machine that bent it slowly until the hilt broke. He explained in court that he’d measured the forces, and was satisfied that a human wrist was not capable of producing them. He declared that the pieces of plastic were unlikely to have come from a stabbing. ‘I was sitting in court listening to this,’ recalls Val, ‘and it was just fundamentally wrong. We had another murder in the laboratory at the same time with four knives. Three of the four had broken in exactly the same way at the hilt.’

  The plastics expert had investigated a dynamic event of life and death, steel on bone, plastic on flesh, in a controlled but unrealistic laboratory environment. For Val, that is a scenario fraught with problems. ‘Murder is not a replicable experiment. Every one is unique.’

  All the time maintaining their innocence, the Reed brothers were both sentenced to a minimum of eighteen years’ imprisonment. As they were led from the court, they grinned and thanked the judge while Hoe’s mother Maureen cried in the public gallery.

  Not long after their conviction, Justice Weir acquitted Sean Hoey of the Omagh Bombing and LCN profiling was put under intense scrutiny. Though its use was reapproved by the CPS in January 2008, enough doubt had been sown that, on 20 October 2009, the Reeds appeared at the Court of Appeal. Their lawyer argued that Val Tomlinson had overstepped the mark when she speculated at the original trial on how the Reed brothers’ DNA got on to the pieces of plastic recovered from the scene.

  At the appeal of the Reed brothers, in October 2009, the court heard from Bruce Budowle, a former FBI forensic scientist. Budowle argued that LCN DNA profiling was inherently flawed and that its results were not always reproducible. ‘The confidence in it has not been assessed,’ he said. He accepted that the bits of plastic came from the knives of the murderers, but the Reeds’ DNA could have been the result of secondary transfer – that is, they could have touched someone who then touched the knives.

  As well as knowing the latest research-based theories, forensic scientists like Val must draw on a database of professional experience to understand what they see. Gill Tully says, ‘There have been some interesting judgments from the Court of Appeal in recent years which have really pointed forensic scientists to give opinions informed by experience rather than giving statistical evaluations, which is slightly bizarre for the scientist, although you can see where Their Lordships are coming from.’ But, as Sherlock Holmes knew way back when, ‘There is a strong family resemblance about misdeeds, and if you have all the details of a thousand at your finger ends, it is odd if you can’t unravel the thousand and first.’ Val’s testimony, both about the shattering of the knife handles and the DNA traces they contained, was based on years of experience with evidence. It was data and opinion; art and science. And, ultimately, the court believed her: while the review made some recommendations about external validation, ultimately it found the method robust and reliable. The three judges at the Reed brothers’ appeal decided that the circumstantial evidence was powerful enough to make doubt unreasonable, and upheld their convictions. They thought that Val’s professional opinion on how the DNA had got on to the plastic was ‘not only possible … but essential’.

  The case against the Reed brothers had solid corroborating evidence – such as the fact that Peter Hoe had inflamed the pride of David Reed by knocking him to the floor with a light punch in a pub a fortnight before the murder – as opposed to the case against Sean Hoey, which relied nearly solely on LCN DNA. Valuable lessons had been learnt about the place of DNA in criminal investigations as a key component of a case, but nevertheless, only a component. More such lessons were to come.

  In 2011, a woman was brutally raped in Plant Hill Park, Manchester. DNA taken from a swab of the victim linked the crime to Adam Scott, a 19-year-old from Plymouth, who was duly arrested. He was incarcerated in a special segregation wing for rapists and paedophiles, and verbally abused by inmates. But he was adamant that he’d been hundreds of miles away in Plymouth on the night of the crime, and had never even set foot in Manchester.

  After four and a half months in jail it emerged that Adam Scott had been the unfortunate victim of laboratory cross-contamination. Some months previously he had been involved in a ‘spitting incident’ in Exeter, after which police took a swab of his saliva. Scientists placed the swab in a tray at the LGC Forensics laboratory, which was re-used for the swab of the Manchester rape victim. Scott’s mobile phone records confirmed that his phone had been in Plymouth when the rape took place.

  Andrew Rennision from the government’s Forensic Science Regulator said, ‘The contamination was the result of human error by a technician who failed to follow basic procedures for the disposal of plastic trays used as part of a validated DNA extraction process.’ Adam Scott’s case echoed the strange case of the ‘Phantom of Heilbronn’, a seemingly superhuman female serial killer whose DNA was found at the scene of robberies and murders across Austria, France and Germany in the 1990s and 2000s. In 2009, when the DNA appeared on the burned body of a male asylum seeker in Germany, the authorities concluded that the ‘phantom’ was simply the result of laboratory contamination: the cotton swabs used for DNA collection were not certified for the purpose, and were eventually traced to the same factory, which emplo
yed several Eastern European women who fitted the DNA profile of the ‘phantom’.

  As with a real fingerprint, a genetic fingerprint should not be enough to secure a conviction on its own. According to Gill, ‘DNA doesn’t lie. It’s an exceptionally good lead and exceptionally strong evidence but there is human interaction in the process [of profiling]. So the error rate is exceptionally low but it’s not zero … DNA shouldn’t be a lazy way to not do an investigation.’

  If in some cases DNA has become a crutch for the police to lean on, in many more it has opened up outlets for their energy, giving them the chance to solve cases both new and old. If DNA found at a crime scene doesn’t produce a perfect match when it’s run through the national database, it’s no longer the end of the line. Because blood tells more than just one person’s story.

  Familial DNA searching was developed at the FSS by Jonathan Whitaker when he re-examined a grim cold case. In 1973 three 16-year-old girls had been raped, strangled and dumped in woods near Port Talbot in South Wales. After an exhaustive investigation into 200 suspects, police had made no arrests. Then, in 2000, Whitaker used the 28-year-old crime scene samples to develop a DNA profile of the suspect. He ran the profile through the national database, and turned up a blank. Then, a year later, he was struck by an interesting idea. Could there be a family member on the database with a similar profile? He sought permission to search and found a profile with a 50 per cent match. The offender was on the database for car theft, but Jonathan Whitaker was convinced his family tree housed a far more heinous offender. Joseph Kappen, the car thief’s father, who had died from lung cancer ten years previously, became the prime suspect. An exhumation order was granted and Whitaker was able to analyse DNA from his teeth and femur. It matched and, although the criminal could not be punished, the triple murder was finally solved.