Flaws found in many police DNA samples

Up to half the DNA samples of suspected criminals submitted for testing by police are inaccurate, illegal, or useless, police chiefs have warned.

Failure to submit properly samples of blood, semen and skin, taken from suspects or found at crime scenes, is said to be undermining the fight against crime. Many mistakes were found with samples submitted by 10 of the 43 forces examined by the Home Office. The remaining 33 forces' information was right in most cases, Police Review reports.

Collecting and storing DNA information is one of the key weapons in catching and convicting criminals, particularly repeat offenders such as burglars, rapists and killers. But David Coleman, the Association of Chief Police Officers' spokesman on forensic science, highlighted three "areas of concern" in DNA sampling.

He said many of the mistakes were made because officers did not label samples properly. Others wasted money by submitting duplicates and some forces did not destroy innocent people's samples, which is illegal.

Mr Coleman said the failures caused delays in obtaining vital intelligence and "may lead to the risk of unlawful arrest for an offence that has already been dispensed with".

There are two million DNA samples on the national database - 1.8 million are from known offenders, the rest were taken from the scenes of unsolved crimes. About 36,000 new samples are being added to the database every month.

The Government is funding a £182m expansion of the sampling process, with a target of 3 million samples by 2004.