Friday, July 30, 1999 Published at 09:41 GMT 10:41 UK
DNA evidence boost
The police have used mass DNA testing in 120 cases
The government is proposing that DNA samples taken during large-scale police investigations be kept and used in later inquiries.
Home Secretary Jack Straw will announce plans to change the law to allow a dramatic increase in police use of DNA and fingerprint evidence
The government says this will save time, money and inconvenience.
The BBC's home affairs correspondent Jane Peel says DNA profiling is increasingly being used to catch criminals.
'Caught by dandruff'
Advances in technology have enabled police forensic scientists to make a DNA match on evidence as small as a single hair or a piece of dandruff.
In the past only blood would suffice.
DNA tests have been particularly successful in cases where police have had to test hundreds or even thousands of people.
But under current legislation, the tests have to be destroyed if someone is caught and convicted.
The increasing use of mass screenings meant some people were being approached more than once.
Not only is this a waste of money, but it has sparked fears that people will refuse to give samples on the grounds of duplication.
Mr Straw said the samples would only be stored with the donor's consent, and would be kept on a separate database to the National DNA Database. This contains samples from 600,000 offenders.
At the moment, around 600 matches a week are made on the database, which is the biggest in the world.
Officers will also be given the go-ahead to use electronic scanners to gather fingerprints from suspects rather than relying on ink pads and paper.