Yahoo News Forensic science: the tip of the iceberg?
We all want to live in a world where there is justice; where wrongs are righted, where the system is trustworthy and just works. But we have seen a growing body of reports that raise questions about that system. I was particularly challenged when I started doing research that was based on a murder case tried in 2002, which centred on the presence of trace particles on the victim and in the suspect’s vehicle. In court, the jury heard that these particles were very rare and wouldn’t last on clothing for a very long time – just for a matter of minutes. This indicated that the victim must have made contact with the vehicle seat shortly before their body was deposited at the site where they were ultimately found. On this basis, the jury delivered a guilty verdict. When we started exploring and carrying out some experiments on these particles we discovered that they were in fact not rare, but abundant. And they lasted a long time on clothing – many hours rather than minutes. The significance of these particles in that case was completely changed by a series of experiments.
The big challenge for Forensic Science
We have recently seen huge challenges exposed in the justice system; the Randox laboratory cases, the issues around disclosure that have been highlighted by the case of Liam Allen, and the recent headlines on the ‘disclosure crisis’. These appear against the backdrop of the warnings given about the impact of budget cuts on the justice system and on the quality of forensic science. These are all incredibly serious issues, but there is another issue that hasn’t made the headlines, yet. In 2015, the FBI identified that in 96% of the cases that they had looked into where hair analysis was critical, the evidence had been overstated or misinterpreted. Last year, a study that looked at cases upheld by the UK Court of Appeal found that 22% of those cases had ‘criminal evidence’ that had been misinterpreted. Of the reasons cited as to why evidence was misleading in those cases, nearly a third of the reasons were identified as misinterpreted forensic science evidence.
The technological capabilities to measure and classify trace materials have increased, and the accuracy of the measurements that can be made is greater than ever before. But as the Chief Government Scientific Advisor said in his annual report, “New capabilities create other challenges for our existing systems; in particular, our ability to analyse may outstrip our ability to interpret.”
When we find trace evidence, such as explosive residue particulates or a trace DNA profile, at a crime scene or on a suspect, we can often provide good indications about what it is or who it came from. But there are big questions that still need to be answered for us to be able to know what that trace evidence means and how significant it is for a case. There is more on this in my TED talk.
The scale of the problem: the dark figure of misinterpreted forensic science evidence
An added issue is that we don’t know the actual scale of the problem. Studies carried out in the US and the UK have illustrated the cases where evidence was misinterpreted, which have resulted in exonerations. But these are only the cases where the misinterpretation was identified and the appeal case was successful. We are left with a ‘dark figure’ of cases (similar to the ‘dark figure of crime’) where we don’t know if the evidence was misinterpreted nor how many cases this may affect. The cases that have been identified so far are simply the tip of the iceberg.
At the moment, that iceberg isn’t fully acknowledged, and the scale of the problem we face hasn’t been addressed. The significant cuts across all the sectors that have a bearing on the justice system have meant that the research that is needed to answer these questions is not being prioritised and funded.
But just as the breath-taking scale and complexity of icebergs and the oceans are being realised (as the 10.6m viewers of Blue Planet II can attest to), so the scale of the iceberg of misinterpreted forensic science evidence needs to be understood and, critically, it needs to be addressed. To do that we need to harness the best scientific approaches and enable high quality research within the professional and academic science communities.
A solution?
We need a change in our traditional focus, and we need data. We need to focus on the activities and factors that influence the presence of the forensic science evidence, rather than predominantly addressing where or who that evidence originated from. If we can understand these movements and factors better, we can start to provide data to inform the interpretation of what a piece of forensic science evidence means, and its significance when it is found in a certain place at a particular time.
We are showing that it is possible to carry out systematic experimental studies that can offer this type of evidence base that can guide the interpretation of what trace evidence means in a case context, and we have a vision to do a lot more in a dedicated forensic science evidence interpretation lab. For example:
We can show when gunshot residue can undergo multiple transfers on intermediary objects (such as door handles and shopping trolleys) and between people. The data indicates that you can have gunshot residue particles on you even if you’ve never fired a gun.
We have data now that indicates that trace DNA can be identified on weapons. The research is showing that DNA can be transferred indirectly, and that your DNA can be on a knife that you’ve never even touched.
We are seeing when environmental indicators, such as minerals and microscopic algae that are specific to particular environments, transfer to footwear and clothing. Critically the data show that this kind of trace can also persist over long periods of time and can be preserved even if the shoes or jacket are put through the washing machine. This indicates that just because something looks clean, there may still be valuable forensic evidence to be collected.
Forensic Science has a huge amount of value to offer the justice system, but it needs to have a robust and transparent empirical foundation that can underpin the interpretation of what forensic science evidence means in a specific case. To secure this for the future we need to ensure that the resources needed are made available. Until we can do the research to create that foundation, we will continue to face a very significant problem. Without that research, your DNA found on clothing at a crime scene that you’ve never touched or worn, or explosive residue found on your hands on your way through an airport scanner, or the presence of trace particles on a seat in your car, may not be interpreted correctly.
Ruth Morgan is a professor at UCL.
