Omagh trial collapse leads to review of DNA testing

Dozens of serious criminal cases are to be urgently reviewed after the worth of a controversial DNA technique was called into question.

The spotlight will be thrown on a number of high-profile cases, including the disappearance of Madeleine McCann.

The Crown Prosecution Service ordered the re-examination of cases currently going through the courts after the judge who cleared Sean Hoey, the only man charged over the 29 Omagh bombing murders, queried its reliability.

The Association of Chief Police Officers also announced it was suspending its use of the method called "low copy number" DNA.

Question marks now raised over the technique - which has been used 21,000 times since its launch in 1999 - could trigger an avalanche of appeals by criminals who were convicted using the method.

Low copy number DNA allows the genetic profiles of suspects, victims or witnesses to be "uncovered" even when there is only a tiny amount of biological material present.

This is sometimes as small as a millionth of the size of a grain of salt.

The technique amplifies tiny DNA fragments where it is believed that a suspect may have transferred DNA through touch, like the residue believed to have come from cells such as skin or sweat left in a fingerprint.

There have been constant doubts within the scientific community about the merits of LCN testing.

It has been validated only by scientists of the Forensic Science Service, a Government owned company which pioneered the technique, rather than by outside experts.

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In Hoey's trial, the prosecution used the LCN technique to link him to some of the explosive devices in the case.

However, its accuracy was brought into question when a sample taken from a car bomb in Lisburn, Co Antrim, was wrongly linked to a 14-year-old schoolboy in Nottingham.

The judge at Belfast Crown Court, Mr Justice Weir, pointed out that the process is only admissible as evidence in two other countries in the world - New Zealand and the Netherlands.

He said an internationally standardised system needs to be established before the process can be considered accurate.

Yesterday Tony Lake of the Association of Chief Police Officers said: "In England and Wales DNA evidence has to be corroborated by other evidence.

"However, as a precautionary measure the Crown Prosecution Service are currently reviewing the pending cases in which Low Copy Number DNA profiling is to form part of the prosecution case to see whether any may be affected.

"Whilst this is being considered the police are operating an interim suspension of the use of LCN DNA testing service offered by the Forensic Science Service."

A similar review is being undertaken in Northern Ireland at the request of Chief Constable Sir Hugh Orde.

Sir Hugh said the technique is at the very cutting edge of science and had been used in the Hoey trial because of his determination to bring a case.

A spokesman for the Crown Prosecution Service said: "This is a long and complex judgment and we will need to look at it carefully.

"We are currently reviewing the number of live cases that might be affected, so it is not possible to say at this stage how many there might be.

"The Home Office forensic regulator is reviewing DNA Low Copy Number and we will also await that review.

"The use of DNA technology has developed into an extremely powerful tool for preventing, reducing and detecting crime and for ensuring the innocent are cleared."

A spokesman for the Forensic Science Service said of LCN: "We consider it to be a very robust technique which has undergone extensive testing since we began using it in 1999.

"If there had been serious problems they would have come to light by now."