Forensics

by Val McDermid

  The first live case to be cracked using familial searching came in 2004. Michael Little was driving his lorry under a motorway overpass when someone threw a brick from overhead. It crashed through the windscreen and struck Little in the chest. He managed to steer his lorry on to the hard shoulder before succumbing to a fatal heart attack. When scientists fed the LCN DNA from the brick into the database, it produced no direct match, but a familial connection led them to Craig Harman, who admitted his crime and was sentenced to six years for manslaughter. For Detective Chief Inspector Graham Hill of Surrey Police, there was only one reason a conviction was secured: ‘There is no doubt in my mind that without this groundbreaking technique this crime would have remained undetected.’

  In the aftermath of the Harman conviction Alec Jeffreys said that familial DNA searches raised ‘potentially rather thorny’ civil liberty issues. The response has to be proportionate to the crime, striking the right balance between an individual’s civil rights and the need to identify a perpetrator. Familial DNA searching for forensic purposes remains illegal in most countries. In the US it is only allowed in California and Colorado, though a familial search on DNA extracted from a discarded piece of pizza may have helped to find the ‘Grim Sleeper’, a serial killer and rapist who terrorised Los Angeles from the late 1980s to the early 2000s. In the UK it’s only used for investigations into murder and rape. Since the Harman conviction it has led the police to a suspect in fifty-four serious crimes – producing thirty-eight convictions.

  Ethical issues persist. Troy Duster, a sociologist at New York University, points out that because incarceration rates in the US are eight times higher for black people than for white people (for socio-political reasons, including alleged racism on the part of the authorities), familial searches are much more likely to help convict black criminals. The profiles of around two in five of the black men in the UK are on the national DNA database, compared to around one in ten white men. In US, around 40 per cent of the DNA profiles in the federal database are African-Americans, who make up about 12 per cent of the national population. It is predicted that the DNA profiles of Latinos (about 13 per cent of the population) will soon show a similar skew, mainly due to crimes surrounding immigration.

  One way to gradually level the playing field would be to profile everybody. Already the UK national DNA database has over 6 million profiles, a higher proportion (10 per cent) of its citizens than any other country in the world. DNA from everyone arrested (whether convicted of a crime or not) was held on the database indefinitely until a decision by the European Court of Human Rights in 2008 forced a change. In 2012–13 profiles of 1.7 million innocent people were deleted from the database. Alec Jeffreys had called for this in 2009: ‘My view is very simple … innocent people do not belong on the database. Branding them as future criminals is not a proportionate response in the fight against crime.’

  Because so many crimes are committed by repeat offenders, the national database is a powerful police tool. In 2013, 61 per cent of DNA profiles found at crime scenes found matches in the database. The Home Office doesn’t record how many of these matches led to a conviction, but it’s a formidable help to the police forces, some of whom have advocated mandatory profiling. But others believe that would lead to more false assumptions. DNA from several people is often present at one crime scene for perfectly innocent reasons, particularly since scientists can now produce results from such minute quantities.

  This nightmare scenario, along with issues of personal privacy and the huge bureaucratic cost of profiling 60 million people, is probably enough to put the matter to rest for now. In addition, some worry that mandatory profiling would make it easier for criminals to frame innocent people. A defence barrister once put the framing idea to Val Tomlinson in court, claiming that his client’s LCN DNA had been planted at the scene by an anonymous other. To prove it, he asked Val a hypothetical question:

  ‘If you were going to set somebody up for this how would you go about doing it?’

  ‘I don’t think I could,’ said Val.

  In Val’s experience most set-ups fall down on basic points. ‘Children go over the top when they are trying to cover up for their mistakes. And you tend to find that people who frame others distribute too much blood in the wrong way, or a whole bucketful of glass instead of the two little pieces which is what you would expect to persist on a piece of clothing recovered a week after a crime.’ Like any powerful tool, DNA can be misused. But, as always, the analysis of evidence is not simply about the collection of data – whose DNA is or isn’t there – but also about the interpretative skills of the scientists who deal with it. This is what should – and mostly does – protect the innocent.

  Of course, not all criminals want to hide their identities: when political fighters or terrorists commit crimes, they want the world to know who did it. In the Madrid Train Bombings (see p.34), DNA and politics were central to the case from the very beginning. The timing of the attack, three days before the general election, was significant. In the immediate wake of the bombings, the incumbent government claimed that evidence had been found that implicated the Basque separatist group ETA, perhaps hoping to quash speculation that the bombings were a result of Spanish involvement in the Iraq war. But three days later the self-proclaimed ‘military spokesman for Al-Qaeda in Europe’, Abu Dujana Al-Afghan, declared responsibility. ‘This is a response to the crimes that you have caused in the world, and specifically in Iraq and Afghanistan … You love life and we love death.’

  A month later, seven suspects on the verge of a police raid detonated bombs in their apartment, wiping out four of them and one police officer. Scientists could not match the LCN DNA found at the scene (including on a toothbrush), and from other locations, with profiles on national databases. A judge ruled that the scientists should use the DNA to determine whether the suspects who were still at large were of North African or European descent. This would help investigators finally settle whether their targets were members of Al-Qaeda or ETA.

  But intermarriage between southern Europeans and northern Africans on both sides of the Mediterranean made differentiating between the two all but impossible using the technology current at the time. Forensic geneticist Christopher Phillips developed a new technique, and was able to conclude that one DNA profile, which did not belong to any of the dead or arrested men, ‘almost certainly’ belonged to a North African. Familial DNA searching later indicated it belonged to Ouhane Daoud, an Algerian whose fingerprint was also found on unused detonator caps in a Renault Kangoo near the site of the bombings.

  While conducting his research into ethnicity, Christopher Phillips was also able to deduce ‘with around 90% predictability’ that DNA from a scarf found in a van used in the bombings belonged to someone with blue eyes. More and more, scientists can discern details about a suspect’s physical appearance from their DNA: traces left at a crime scene can describe the people who were there almost as accurately as an eyewitness.

  It all started with ginger hair. In the early 2000s scientists at the FSS found that if a gene (the melanocortin 4 receptor) is switched off in both parents then the child will have red hair. Gill Tully is cautious about the ethical implications of DNA profiling in this way, but overall, she says, ‘It’s about using things in the right way: when we were developing the red hair test, we had some detectives in Scotland phone us and say, “There’s been a shooting and we know from the ballistics what window the shot was fired from. Around there we found some cigarette butts and got a DNA profile from them. We also have an eyewitness account saying a red-haired man ran away from the building. So before we start doing a mass DNA screen of individuals to see if we can find the person who smoked the cigarette butts, can you tell us if they were smoked by a red-haired man?” We weren’t quite able to do it at that stage but it was quite a nice example of how these things can be used in an ethical and appropriate way to help direct an investigation so that you don’t spend lots and lots of money analysing cigare
tte butts that are entirely irrelevant and were smoked by somebody months ago.’

  Genetic fingerprinting is a powerful indicator of guilt or innocence; the single biggest advance in forensic science since William Herschel and Henry Faulds developed fingerprinting a century before. Much of forensic science is based on subjective interpretation: as explored in the Fingerprinting chapter of this book, experts are sometimes good at finding patterns where they wish to see them, like all human beings. That is a useful skill for a forensic investigator, as long as its intuitive nature is recognised and expressed in court.

  Although human error can always creep in, in its simplest form, DNA pulls us out of the trap of subjective bias, interpreting empirical data using objective probabilities that have been refined for over thirty years. When Gill has unmixed DNA from a crime scene which she matches to a suspect she can safely tell jurors that the ‘probability of observing that profile if it was from someone other than the person of interest would be one in a billion. That’s a conservative estimate that an average juror can get their head around. If you start going into trillions it means nothing.’ But life – and crime scenes – are rarely simple. Where, as Gill points out, ‘you have DNA mixed from two people, which is often the case, then you need to do a more thorough evaluation of strength of evidence and look at the probability of observing that particular set of mixed peaks both if the prosecution hypothesis is true, and if the defence hypothesis is true.’

  There remains a lot more for forensic scientists to learn from DNA. At the moment Val and Gill look at much less than 1 per cent of a person’s DNA to judge whether it matches a profile on the national database. As it get quicker and cheaper, ‘you could theoretically analyse someone’s entire genome’. The possibilities are endless, ‘but there are very, very significant ethical and practical issues to answer before you would want to do that. You certainly don’t want to be using forensic samples to generate information about people’s predisposition to commit crime.’ That’s a profoundly disquieting thought. We already know, for instance, about the existence of a ‘warrior gene’ – present mainly in men – which is linked with violent and impulsive behaviour under stress. We do not, in the twenty-first century, want to return to Cesare Lombroso’s nineteenth-century uomo delinquente, or ‘criminal man’, or the Victorian discipline of phrenology, which diagnosed a predisposition to criminality from lumps on the skull. A nightmare scenario by any measure.

  But, if used proportionately, the future of the genetic fingerprint is more exciting than scary. There are now instruments that can analyse DNA in less than an hour and a half, making it possible to run the profile of an arrested suspect through the national database before they are released from custody. If the search produces a match to profiles found at scenes of unsolved crimes, police have halted a serial offender. Gill explains, ‘Habitual burglars, if they are caught, sometimes know the DNA is going to get them so when they are out on bail they will commit more crimes to look out for their family while they are away. Then they’ll ask all those crimes to be taken into account and they’ll serve their sentences concurrently. There are a few really key cases where it could have potentially prevented serious crime, where people had come into police custody then gone out and committed a serious crime. Whereas if the police had had a DNA result quickly they would never have been bailed.’

  At the moment analysing the minute quantities of DNA usually found at crime scenes takes quite a bit longer than an hour and a half, but ‘the time will definitely come, and it won’t be that far away, when you’ll be able to identify a suspect, and not only identify them but potentially go around to their address before they have fenced off all the gear that they’ve just stolen. It could then be returned to people, things of sentimental value and so on. The potential to do this really, really quickly is not that far away. It’s not going to be long.’ Let the burglar beware.

  EIGHT

  ANTHROPOLOGY

  ‘I have seen many strange things, but where shall be seen a thing stranger than this? … Two lusty porters brought to the witness stand sundry big boxes containing the mortal remains of the woman: they were packed in jars, cigar boxes, paper boxes, tin pails; there were fragments of dry bones, fibers steeped in grisly solutions; anomalous dung and granules, pieces of rag and cloth … but there, all the time, sat grave professors in the witness chair, interpreting and recounting until, as you listened, the dry bones and dust took on form and life; the rags grew into garments, the garments were fitted on the figure.’

  Julian Hawthorne on the Leutgert Murder Case of 1857

  We’re all fascinated by what forensic science can do. It makes for seductive crime fiction and thrilling TV series. But sometimes we get so caught up in the glamour of the storytelling that we lose sight of the enormity of the crimes that confront investigators in the field. No group of scientists faces that stark reality more than forensic anthropologists. Bloody wars and natural disasters are their front line; bringing home the dead is their vocation.

  Kosovo, 1997. As the twentieth century came to a close, one of its most vicious conflicts ripped the Balkans apart along ethnic and religious lines. Each side demonised the other, seeing the enemy as subhuman, as vermin that had to be cleansed to make the land pure again. It’s a mindset that inevitably leads to atrocities, and there was no shortage of those in that time and place. I’ve spoken to some of the investigators who arrived in Kosovo after the war was over; the shadow of things they still cannot speak of lurks in their eyes.

  Picture this. A tractor and trailer were making their way down from the Kosovan hills. At the wheel, a farmer who had decided the fighting was growing too close for comfort. In the trailer, all eleven members of his family. His eight children, aged from one to fourteen, squeezed in beside their mother, their grandmother and their aunt. The weather was fine and clear and, in spite of the fear that had become a permanent part of their lives, the family were talking quietly among themselves.

  But their attempt to flee to safety had put them in harm’s way. Somewhere close by, an enemy lay in wait with one of the most lethal weapons people can face on the battlefield – a rocket-propelled grenade launcher. A child can learn to use it in an afternoon; there are YouTube videos that demonstrate that. It’s cheap, effective, highly portable and lethal. It’s an icon of asymmetric warfare, the mainstay of guerrilla wars since Vietnam. It often obliterates its targets completely.

  Out of nowhere, a grenade hurtled towards the family and exploded, destroying the trailer and annihilating all but one of the passengers. The farmer survived, though one of his legs was wounded in the blast. Shocked and desperate, he dragged himself out of the firing line. Later, under cover of darkness, he crawled around the site of the explosion searching for the other eleven members of his family, collecting as many bloody and broken body parts as he could find. A devout Muslim, he was driven by the need to bury his family as soon as he could. Somehow, in spite of his grief and trauma, he managed to dig a shallow grave and put their remains in the ground.

  Eighteen months later, forensic anthropologist Sue Black arrived in Kosovo with the British forensic team to collect evidence for the UN International Criminal Tribunal for the Former Yugoslavia in The Hague, the first international war crimes trial since Nuremberg and Tokyo in 1945–8. So far, 161 people have been indicted by the tribunal. Seventy-four have been sentenced, and twenty are still being tried. The former president of Yugoslavia, Slobodan Milošević, died in 2006, before he could be sentenced for crimes against humanity. The role of the British team in Kosovo was to exhume mass graves and investigate acts of genocide.

  Forensic anthropologists excavating a mass grave in Kosovo

  When Sue met the farmer she found him ‘the quietest, most dignified man I’ve ever met’. Sue and her colleagues were seeking key evidence of an unprovoked attack on the people in the trailer. But distant courtrooms in the Netherlands meant little to the bereft farmer. He wanted to mourn his family properly. He thanked the team f
or coming to exhume the remains of his family, explaining his pain that Allah couldn’t find the individual members while they were lumped together in a common grave. He asked her to dig up their remains and bring him back eleven body bags, so he could bury each one separately.

  He couldn’t have known it, but he had at his service one of the world’s leading experts on the bones of children. Sue sent everyone away except for the X-ray technician and the photographer and laid twelve sheets by the makeshift grave. ‘We needed the twelfth because I knew there would be elements I couldn’t identify with certainty. I was also aware that it would have been very tempting to just put a little bit of something in each of the bags and the father would have been appeased. Of course, that would have been completely and utterly morally incorrect. But more importantly it also would have been judicially unacceptable. We are there for forensic purposes, not humanitarian. Our job is to collect evidence, analyse evidence, present evidence and, when we go into court, to be able to justify what we have done.’ She imagined a defence expert opening one of the body bags and finding that the material was not what it purported to be. It would completely discredit the prosecution.

  So she set to work. After eighteen months, decomposition had done its work and most of the material she had to deal with was bone. The adults were relatively easy to distinguish from one another because they were bigger and there were fewer of them. The eight children were much harder. Sue painstakingly separated the fragments. After several hours she had identified the six youngest children. All that remained were two sets of upper limbs, which had belonged to 14-year-old twin boys. ‘There was nothing else of them. Just humeri and clavicles. But one of the sets of upper limbs was attached to a Mickey Mouse vest. I said to a police officer, “Go and ask the dad which of his children liked Mickey Mouse. Don’t say which of the twin boys or anything leading like that. If he comes back with the name of one of the twins, then we can separate them.”’ The officer came back with the father’s reply. He’d named one of the twins. ‘“He adored Mickey Mouse. That’s his vest.”’ An hour later Sue brought the twelve body bags to him. ‘That’s what he wanted more than anything. Giving him his family back was the absolute and utter least we could do, considering what he’d been through.’