Less than 1% of crimes are solved using the DNA records stored on the government's DNA database, a parliamentary select committee said in recommending that DNA profiles of innocent subjects should be kept for a maximum of three years
"We are not convinced that retaining for six years the DNA profiles of people not convicted of any crime would result in more cases being cleared up, let alone more convictions obtained, than retaining them for three years," said the chairman of the Home Affairs select committee Keith Vaz.
Vaz said no one could say exactly how many people had been convicted because of DNA evidence in the database. "It appears that it may be as little as 0.3%," he said.
Evidence before the committee showed that some 4.9 million crimes are reported each year. Suspects were charged in about 1.3 million cases. In these detected crimes DNA matching was used in about 33,000 cases, compared with about 45,000 in which fingerprint evidence played a part. Home Office estimates for 2006 suggested only half of the 33,000 cases led to convictions.
Despite this, MPs said DNA profiling and matching are vital tools in the fight against crime. But that alone is insufficient for the Crown Prosecution Service to bring suit against a suspect, they found.
MPs are aware that DNA evidence has linked serious criminals to their crimes, even years after the event. "We note that the reason for retaining personal profiles on a database is so that the person can be linked to crimes he/she commits later," Vaz said.
MPs accept police arguments for keeping DNA samples of "minor" criminals. Enough people went from minor crimes to more serious offences that the database would be less effective if DNA profiles associated with minor crimes were deleted early, they said.
MPs' recommendations will be put forward to amend the Crime and Security Bill before parliament.