Study backs controversial DNA method

A controversial technique for obtaining DNA profiles from tiny samples is scientifically sound, an independent review concluded today.

The study, commissioned by the Government last year after doubts were raised over the reliability of low template DNA testing, made a series of recommendations for improving the collection and interpretation of samples.

Professor Brian Caddy, who led the review, said the technique is fundamentally safe, but is not being used as effectively as it might.

Low copy number (LCN) DNA testing - a particular technique within low template analysis - hit the headlines last December when the judge in the Omagh bombing trial questioned its scientific validity.

Mr Justice Weir expressed doubts over LCN testing after it wrongly linked a sample taken from a car bomb in Northern Ireland to a 14-year-old boy in Nottingham.

The Police Service of Northern Ireland (PSNI) suspended its use of LCN testing after the Omagh trial but the technique continued to be used by prosecutors in England and Wales.

Low template testing can build up a DNA profile from just a few cells, which can be deposited by something as simple as holding a glass or door handle but are too small for standard DNA profiling.

Today, the Caddy Review made 21 recommendations for improving the use of low template testing, among which are the establishment of a programme to educate police scenes of crime and forensics officers on collecting samples for low template analysis; national standards for the interpretation of low template results and the development of an advisory panel to guide the courts on how to interpret low template DNA evidence.

Any DNA profile obtained using low template techniques should be presented to a jury in a criminal trial with caveats, the report said.

Professor Caddy said the report's authors are happy that the science of low template DNA testing is sound and secure.

"We also believe that the work on the interpretation of DNA is good, but needs to be developed more," he said.

"The drive is towards the setting of standards of recovering DNA from crime scenes, and having set those standards, making sure they are properly implemented."

Andrew Rennison, the Forensic Science Regulator, said he is confident that the technique is safe for use in the courts.

"Scientific evidence has to be considered on a case-by-case basis by the prosecution, defence and the experts, and you can never say the science in a case proves something absolutely," he said.

"I'm perfectly satisfied that we should be using these techniques.

"I'm satisfied the science is safe and fit for purpose, but there is work to be done around collection and interpretation."

He refused to comment on previous occasions, such as the trial of Sean Hoey for the Omagh bombing, where low template testing was called into question.

"I'm not concerned about previous cases or current cases. I'm concerned with producing something that's better than it is now," he said.

Mr Rennison said he is in discussion with the Crown Prosecution Service, National Policing Improvement Agency and Home Office, and will make his own recommendations on low template testing to the Government soon.

Home Office minister Meg Hillier thanked Prof Caddy and his team for their work.

"I am very pleased that they conclude that the science behind the technique is robust," she said.

Police forensic teams and scenes of crime officers need a national standard of training to make them aware of the potential and limitations of the low template technique, Prof Caddy said.

"What happens at present - they will recover DNA from the crime scene by a particular method in that particular police force," he said.

"They need to be trained more to identify whether it will be LCN DNA, and make sure there's no contamination involved."

The study pointed out that failure rates for low template DNA analysis are high - one police force estimated success rate in achieving a full profile at about 6%.

Because of the minute quantities of material involved, the potential for contamination by outside sources of DNA - from a police officer or forensic laboratory worker, for example - is much greater in low template testing than in standard DNA techniques.

In the light of this, the review called for the establishment of a national standard for "DNA clean" crime scene recovery kits.

Dr Andrew Linacre, of Strathclyde University, who also took part in the study, said low template analysis presents particular challenges to the forensic scientist: because of the tiny quantities of material under examination, statistical anomalies are not unusual.

These would not lead to one person being wrongly identified as another, he said, but there needs to be more research to reach a consensus on how to interpret unexpected results.

The report said the Forensic Science Regulator should develop a consensus between the three providers performing low template analysis on how to interpret low template DNA profiles.

The regulator also needed to explore the means of establishing a professional organisation for forensic science providers to enable them to develop common standards and share research without compromising the commercial value of their work, the study said.

Chris Sims, Chief Constable of Staffordshire Police the Association of Chief Police Officers' (Acpo) spokesman on forensic science said: "Professor Caddy's review of the science of low template DNA profiling provides a helpful explanation of the science and a basis for improving the contribution of DNA profiling to crime investigations.

"The service wants and needs reliable and sound DNA techniques. ACPO looks forward to working with the forensic science regulator and other agencies to take these recommendations forward."

Professor Allan Jamieson, director of The Forensic Institute in Glasgow, said there was no doubt that very small amounts of DNA could be amplified.

"The real issue is: do we know what it means when you see a profile?" he told the BBC.

"For example, when you mix two people's DNA together, it's like mixing the coins in their pockets together. They end up on the table and you have to say which coin came from which person. You simply can't do that."

Asked whether this sort of DNA evidence should be used in court cases, he said: "I agree to some extent with the CPS who say it's a case by case basis."