Police misuse of fingerprinting and DNA techniques is helping suspects to avoid prosecution and conviction, a new report says.

Accused people were able to explain how their marks were found at a crime scene because of "inept" work by officers, according to Her Majesty's Inspectorate of Constabulary (HMIC).

And similar warnings made six years ago had not been heeded, the report added.

Home Office police minister John Denham said he was disappointed at the findings of Wednesday's report, which studied 43 police forces in England and Wales.

Many forces still have a great deal of difficulty in managing the process of turning identifications into detections

David Blakey, HMIC

And the Association of Chief Police Officers' spokesman on forensic science, David Coleman, admitted there was "still much to be done".

He added that the slow progress noted by the HMIC was being addressed but that it was a "long-term project requiring substantial further investment".

The HMIC's David Blakey said despite the money being invested in forensic science, forces still needed to take steps to use it in day-to-day police practices.

Remarking that the HMIC made the same demands in 1996 and 2000, he said: "Things are improving but sometimes too slowly."

He said suspects were able to explain the presence of a fingerprint or stain and throw doubt on any prosecution.

"Concern has been expressed from a number of quarters that inept interview techniques and the inappropriate disclosure of evidence to defence representatives prior to interviews may be one explanation for a high number of legitimate access outcomes," the report said.

'Poor quality'

Similarly, police administration delays and poor information was blamed for preventing convictions in cases where scientists had made a match on DNA or fingerprint evidence.

The report added: "Many forces still have a great deal of difficulty in managing the process of turning identifications into detections and this is rooted in a paucity of quality performance information.

Denham said police should have done better

"There are significant delays in most of the forces assessed in commencing an investigation following receipt of the identification."

Mr Denham said: "It is disappointing that police forces have not done more to implement the recommendations of HMIC's (2000) report.

"I have asked HMIC to monitor progress in this area and provide an update by the end of the year."

He said better training and equipment plus the advances in forensic science were "extremely valuable resources in the fight against crime."

Multiple identities

The Forensic Science Service, in Birmingham, has been given an extra �187m to help it reach its target of DNA profiling 3m active criminals by April 2004.

It has also invested �100m in setting up the National Automated Fingerprint Identification Service.

Mr Blakey also called on chief officers to "champion" forensic science to help deliver the desired convictions.

And the report also noted that too many convicts were listed more than once in the National DNA Database because police failed to filter out multiple identities.