Lacking a full set of prints

A police DNA database is little use if it is incomplete, says Barry Mason

From today, the police have another tool in their fight against rising crime: the Criminal Justice and Public Order Acts now empower police to take DNA samples from people arrested and charged with offences ranging from shoplifting to murder. The samples, which can be taken by force, may be obtained by using a swab to remove saliva from inside the mouth, or pulling out or cutting off a strand of head hair.

This important increase in police powers improves the thrust towards a better intelligence-based system and will, in theory, enable the police to compare people against other people, and people against stains found at the scene of a crime or on a victim.

DNA checks will allow blood, semen, skin tissues or saliva to be scientifically compared by scene-of-crime officers and later at forensic science laboratories.

Genetic fingerprinting should provide the police with an intelligence database whereby the chances of escaping detection are virtually nil for those who commit sexual offences, violent assault or murder.A subsequent conviction, of course, will depend very much on the accuracy with which the tissue samples are obtained, stored, analysed and scientifically presented at court.

But are the police ready for this dramatic power, which many see as another infringement of civil liberties? Certainly the police need all the improvements they can get in preparing forensic evidence, given the catalogue of own goals that has resulted in many innocent people being convicted, released from prison and paid huge sums of compensation from the public purse.

In the past, important forensic evidence has been lost or ruined through inept handling by ignorant or inexperienced police officers. In the West Midlands force, training is under way to teach officers - and indeed the growing numbers of civilian scene-of-crime investigators - to be more aware of vital evidence that may have been left at a burglary or on the victim of a sexual assault.

Training is not the only problem area of preparation, though. Although the legislation allows DNA samples to be taken for all recordable offences, the size of that cataloguing taskwould swamp the scientists. The Association of Chief Police Officers has thereforedecided that samples will be taken only in respect ofserious crime, such as grave assault, sex offences and burglary.

The police are enthusiastic about what they see as a breakthrough in obtaining safe convictions.Over five to ten years, seasoned detectives say, there will bedramatic improvements in detection rates.

This should be so. But the ACPO approach of restricting the taking of samples is a clue to a third serious problem: the huge costof obtaining samples from every person the police are entitled to take DNA from - not to mentionthe cost of retrieving, storing and analysing millions of samples.

The flaw with the whole concept is that by not including all offenders in the system, many will escape conviction. During 1994 more than 30,000 crimes, including nine murders, were recorded in the Birmingham North division of West Midlands police - an area covering a population of 450,000 and including half of the city's council housing. In excess of 300,000 crimes were recorded for West Midlands police as a whole.

Parliament has given the police the legislative power to improve their performance by scientific means, but it has not given them the confidence that they can financially achieve it.

The writer recently retiredas a chief superintendent with West Midlands Police.