“We’ll be able to give the ‘who’ with the ‘what cell it came from’ information. And that’s very powerful.”
New forensic technology which can identify DNA from a single cell could be a “game changer” in helping solve sex crime cases, according to experts. The SCAnDi project’s Scottish scientists claim that the method can identify who the sample came from as well as the body part from which it originated.
Prosecutors think that juries’ decision will be aided if experts are able to provide DNA testimony with a greater degree of certainty. According to experts, this could result in fewer injustices and more convictions in cases involving sex crime.
The current goal of the technology’s creators is to make the procedure reliable enough to be applied in court. Samples collected from crime scenes often contain a mixture of DNA from different people.
The scientists think their new tool will help “unmix” the DNA to determine who and where it came from. Ashley Edwards KC, Scotland’s principal Crown counsel, spoke to the BBC about how she believes this could play an important role in the prosecution of sex crimes.
She said: “Before we run a trial we will consult with the forensic scientists. The question we often ask is: ‘Can you tell us who has donated the sample, where it has come from?”
“The DNA of the mix involved usually the potential accused and the complainer, but they can’t often tell us the sources of the sample. That’s almost a real game changer. The more certain the scientists can be, the better it is for a jury.
“They can say ‘this is what I’ve found and this is what it means’ rather than ‘it perhaps means this, or it perhaps means that’.”
Prof Dame Lorna Dawson from the James Hutton Institute in Aberdeen is one of the lead scientists and as helped to put some of Scotland’s most dangerous murderers behind bars. She believes it will provide more secure and more accurate information which can help secure a conviction.
She told the BBC: “The data the research will generate will give much more confidence in working out how DNA got to be at a crime scene, and which part of the body that DNA came from… so where, what and who contributed to that crime.”
She said more 45% of the DNA samples collected by police were mixtures. She added: “To work out who left behind the DNA, we need to work out what type of cell that DNA came from. We’ll be able to give the ‘who’ with the ‘what cell it came from’ information. And that’s very powerful.”
Prof Lawson spoke on how it could be used on a case where a man was accused of strangling a woman. She added: “Are we able to differentiate the DNA of the skin cells as coming from his hand and the victim as coming from her neck? With this methodology we’ll be able to work out who did what.”
Although the tool is not “court ready”, further tests will be undertaken on forensic samples in live cases. Sandy Brindley, chief executive of Rape Crisis Scotland, said the technique could have “a profound impact” on prosecutions for sexual offences in Scotland.
Speaking on the BBC’s Radio Scotland Breakfast, she said: “What we see in some cases is the person accused of rape dismissing DNA evidence, claiming for example it was accidental contact, it was in a social situation, it was brushing past someone in a hallway.
“If we are able to pin down that the DNA is coming from somebody’s vagina or somewhere else intimate it really stops accused people being able to make that kind of claim.”