Page last updated at 09:21 GMT, Friday, 11 April 2008 10:21 UK

DNA technique 'fit for purpose'

Crime scene
The technique has been used in high-profile cases around the world

A controversial method of obtaining DNA profiles is "fit for purpose" in court, an independent review has concluded.

The government-commissioned study said low copy number DNA analysis, which can establish a profile from just a few cells, was "scientifically robust".

But it recommended improvements in how police forensic teams collect the cells to ensure there is no contamination.

Use of the method was briefly suspended last year after the Omagh bombing trial judge questioned its credibility.

Professor Brian Caddy's report concluded the technique was fundamentally sound, but not being used as effectively as possible.

Omagh trial

During the Omagh trial, Mr Justice Weir expressed reservations about low copy number (LCN) DNA testing.

The technique... is scientifically robust and appropriate for use in police investigations
Professor Caddy

The Police Service of Northern Ireland suspended its use after the acquittal of Omagh bomb suspect Sean Hoey.

Police in England and Wales also suspended the technique, but it was reinstated as admissible evidence after a review of relevant cases by the Crown Prosecution Service found no problems.

However, fears remained that dozens of high-profile convictions secured with the help of the technique - including for murder, rape and terrorist offences - could be unsafe.

Professor Caddy, commissioned by the government's Forensic Science Regulator, made 21 recommendations in his review.

National standard

These included establishing a national training standard for police forensic teams and scenes of crime officers on collecting samples, and ensuring there is no contamination.

Because of the minute quantities of material involved, the potential for contamination by outside sources is much greater.

The review called for a national standard for "DNA clean" crime scene recovery kits, and for a consensus between the three forensic science firms who operate the technique on how to interpret results.

LCN DNA evidence has been used by the Forensic Science Service since 1999
It enables DNA profiles to be produced from minute amounts - often invisible to the naked eye
The tiny particles used vastly increase the potential for contamination

It recommended an advisory panel guide the courts on how to interpret such low template DNA evidence and said any profile obtained using the technique should be presented to a jury in a criminal trial with caveats.

Professor Caddy said: "I am satisfied low template DNA is fit for purpose within the criminal justice system.

"I found that the technique, as developed by all the forensic suppliers, is scientifically robust and appropriate for use in police investigations."

Failure rates

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

Graphic - How LCN DNA testing works

He is in discussion with the Crown Prosecution Service, National Policing Improvement Agency and Home Office, and will make his own recommendations to ministers soon.

Home Office Minister Meg Hillier also welcomed the reports conclusion.

Paul Hackett, from the government's Forensic Science Service, said the report was a "ringing endorsement" of the technique, which had the support of all agencies involved.

"It is very much case dependent and I think broad-brush statements about its reliability are somewhat inaccurate," he said.

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

LCN DNA evidence has been used in high-profile cases around the world, including the Peter Falconio murder trial in Australia, that of serial rapist Antoni Imiela in the UK, and the search for missing child Madeleine McCann.

Case by case

Forensic expert Professor Allan Jamieson, who questioned the validity of LCN DNA when he gave evidence for the defence in the Omagh bomb trial, said its use should be carefully considered.

"The real issue is: do we know what it means when you see a profile?" said Prof Jamieson, director of The Forensic Institute in Glasgow.

"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."

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