Guilty until proven innocent

DNA evidence can free the innocent as well as convicting the guilty
14 February 2018

Interview with 

Carole McCartney, Northumbria University


The window of a prison cell


Forensic genetic evidence can be used to help police put guilty people behind bars, but it can also be used to prove that a convicted criminal is actually innocent. But, as Kat Arney discovered, it’s not just about big-name famous efforts like the US Innocence Project, which has used DNA to exonerate more than 350 people of crimes they didn’t commit. Carole McCartney, a reader in law at Northumbria University, is particularly interested in making sure DNA evidence is used from the very beginning to protect the innocent as well as prosecute the guilty...

Carole - One of the things that we also know about DNA is that if you use it at the beginning of an investigation, it can ensure that innocent people don’t get convicted. Often, that is forgotten because the attention is taken by getting innocent people out of prison. Well it would be quite good if we didn’t put them there in the first place and I think DNA has played a very important role in preventing wrongful convictions as well as very important role in exonerating people who’ve been wrongfully convicted.

Kat - So the kinds of people that have been released under the innocent project and the sort of work that you’ve been involved in, tell me about those. What are the sorts of cases that get taken up to say, “Actually, we don’t think this person did it and we think we can prove it.”

Carole - One of the difficulties of course for the people who are in prison is that forensic evidence is really only collected in the more serious crimes. So your murder, your rape, sexual violence is where you're going to find forensic evidence and to find that it’s been retained as well is important.

So of course, those people who have been convicted of lesser crimes, non-violent crimes and so forth, DNA very rarely plays a role in those sorts of investigations. So if you’ve been wrongfully convicted of that, DNA is not going to save you.

Kat - So if you haven't done your tax return, there's no forensic DNA going to get you out there.

Carole - I mean, for domestic violence, if you beat your wife, of course, the DNA is not going to save you there because DNA is going to be on your wife anyway and so forth. So, it’s only very small amount of crimes for a start that DNA is ever going to come to your rescue.

And you'll find that it can come to the rescue most often where lots of unreliable evidence has been used to convict somebody and we know now unreliable evidence to be things like eyewitness identifications, forced confessions we know so much more about now. But also importantly, other forensic science, even other DNA science that has been used to convict people that we can now subsequently go back and say, “Well, that wasn’t valid. That wasn’t reliable. That wasn’t robust.”

So things like bite analysis, hair analysis, but even the earlier versions of genetic science that we’ve come on so much more, the science has developed so much more now that we can perhaps determine that people didn’t contribute to a DNA profile now that we couldn’t have done before and so forth. So DNA can correct the mistakes of forensic science in the past but also other unreliable forms of evidence as well.

Kat - So, if you're trying to prove someone’s innocence, so you need the forensic data from the crime scene and you need a sample from them, how do you then go about kind of getting them back into the system to get someone to look at this again?

Carole - Well, it’s very difficult. I mean in the UK, it’s particularly difficult and we even have a body that’s been established to look at alleged miscarriages of justice. So, if you lose your appeals, you can go to the CCRC – the Criminal Cases Review Commission - and try and get them to re-investigate things. And if they think there's a potential for forensic evidence to be able to assist in determining whether this was a miscarriage of justice or not then they might be able to undertake that testing.

One of the critical problems there though that we found over the years is there's no requirement, no legal requirement for them to keep this evidence. So if you're convicted, lose your appeals and so forth, why are the police going to hang on to their evidence? And of course, when we had the forensic science service, the forensic service would keep it all in a nice store cupboard and labelled and everything. But they don’t exist anymore. So now, 43 police forces decide, do we bother keeping this? And very often of course, they decide not to. So, it’s very, very difficult.

Kat - That sounds like a significant justice issue if evidence is being destroyed but might later lead to someone having their conviction overturned.

Carole - Yeah, it is!

Kat - It’s bad!

Carole - It is very bad and I think it’s going to get worse before an awful lot more attention. There's a few people trying to draw attention to this as researchers working on this. There was the very big case of Kevin Nun where in Kevin Nun’s case, he wants some DNA testing done but he can't get the police to give him the evidence. And they’ve said, “Well actually, there's no requirement for the police to go and search for evidence when you’ve been convicted and you're in prison.”

The police don’t keep on investigating things, but of course, there's an individual in prison. How are you going to get the evidence or find the evidence? You can't so you have to call upon the police and the police don’t have to do it so you end up with an impasse.

Kat - What are some of the most interesting cases that you’ve come across that have been solved or have been resolved through the use of DNA to exonerate someone?

Carole - DNA very often is about identification so it’s, was it person A or was it person B? And DNA is very useful obviously in being able to say, “Well, it was person A’s DNA, not person B’s.” The difficulty with cases is, that doesn’t often tell you then, did they commit a crime? It just tells you that that was their DNA.

So, we have cases where people’s DNA has been found in supposed crime scenes. But it doesn’t tell you how their DNA got there or what they were doing when their DNA was found or when they put their DNA there. And I think increasingly, we’re going to have appeals on this basis.

We all know for example the taxi driver who had a very severe skin complain to the point where his friends called him “Flaky”. It was not hidden that this taxi driver had a skin complain. But there were victims who had particles of his skin found on him and of course, he then got accused of being involved in these crimes relating to these different victims. Until a solicitor can come along and say, “Well actually, they’ve all been in his taxi.”

It doesn’t sound very savoury but obviously, they’ve been in his taxi and picked up particles from his skin there. So, it’s not always about all the DNA science can tell you who it was. Yeah, but can they tell you what they were doing or how that DNA got there? Appeals are going to be based on this very difficult question that geneticists can't answer.

Kat - What are the biggest risks of using genetic information to convict someone? Is it, there might be an extra match in the database to someone that’s not you or is it this risk of contamination, or just sort of randomly picking up someone’s DNA from their flaky skin?

Carole - I think the science is developed enough. It’s fairly safe and secure now that if you put a full profile or a sample of somebody’s blood into a DNA database, chances of you getting an adventitious match with somebody that isn’t you is very, very slim. So that’s quite easy to pick up.

But contamination at crime scenes is not easy to pick up. So for instance, you know, we’re in this room now. We will probably leave something behind like I don’t have a skin disease but I will still leave behind traces of my skin and so forth that probably, if a crime were to be committed in this room later this afternoon, we would be in the frame. So we would need to be able to explain that we were here before the crime was committed but of course, you can't put a time on the DNA. So, that’s always going to be an issue.

Kat - And one of the other concerns is the ethical issue. I've talked to my podcast before about the ethics of people having their DNA sequenced for some health reasons or personal interest or ancestry, it being stored by companies kept in big databases. How secure is that? What are people doing with it? How much information do they need to know? Do those sort of arguments apply to the data that’s gathered for forensic purposes?

Carole - Well, very much so because it’s the state that are in charge of it and I think anytime the state are gathering information off citizens, there has to be a justification for that. I mean, I've talked to people before and they say to me, “Why don’t you want your DNA on a DNA database?” And I've said, “That’s not the question. The question is, why do you need it? And if you don’t need it, I don’t have to give it to you.”

Kat - If you haven't done anything wrong, what's the problem with giving your DNA?

Carole - If I haven't done anything wrong, well why do you need my DNA? That’s what the answer should be, not, “I haven't done anything wrong. You can have it.” “I haven't done anything wrong. You don’t need it.” Literally you will solve no crimes – I hope – by having my DNA in a DNA database, unless we do do something in this room.

Kat - A bit of light murdering!

Carole - Yeah. But literally, I have committed no crimes. I don’t plan on committing any. Why do you need my DNA? It just makes your DNA database more complicated, unwieldy, bigger, expensive, slower. It’s no point in having it. And that goes for most of the population. I mean, when we started the DNA database, the idea always was to have the active criminal population on the database. The problem with that is we don’t know who they are to just say, “Could we just put your DNA on the database?” So there's always going to be an element of people being caught up in the DNA database.

Of course, what we saw in this country is we’ve got so over enthusiastic that we put nearly every Tom, Dick and Harry on the DNA database until it got taken to the European Court of Human Rights. And they said, “No. This does not make for upholding people’s human rights to privacy and so forth.” If they're innocent, they don’t need their DNA on the DNA database. There has to be a justification for keeping people’s DNA. So we’ve rolled back now.

But whether we’ve rolled back enough, that’s still a debate to be had and of course, it’s always still incremental if you're not keeping an eye on things then. And it’s not just whose DNA ends up on the DNA database and whether we’ve drawn the line in the right place there. I don’t believe we have but others believe we do.

If we do have the line in the right place, it’s also then, what they can do with their information when they’ve got so it’s, “How can it be used for research? Do they use it for familial searching?” So, someone’s partial DNA comes up, they run it through the database to see who’s close to it and then can start tracing family members and so forth which is a legitimate crime investigation tool in its place, but also has very serious ethical issues around whose DNA is on that database and what they're doing with that information.

Kat - Carole McCartney, from Northumbria University - and in case you’re wondering, no we didn’t go on a killing spree afterwards, honest...


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