Unsolved rapes and murders in West Yorkshire could be detected because of world-first advances in DNA technology.

West Yorkshire Police is one of four forces piloting a new computer-based analysis system, DNAboost, which can unravel DNA samples which until now have remained a mystery.

The Forensic Science Service, which has made the discovery, claims the technique will boost detection rates by 15 per cent.

Senior West Yorkshire detectives hope the high-tech methods will further increase the success rate of its pioneering Operation Recall initiative, which has been used to solve major crimes dating back 20 years.

Detective Superintendent Graham Shaw, of West Yorkshire Police's major investigation review team, said Operation Recall had taken them to a very successful level.

"An even more successful level can be achieved with DNAboost," said Det Supt Shaw.

"All the signs are it is going to unmix DNA profiles and identify even more offenders."

The new technique allows forensic scientists to pinpoint DNA samples when more than one individual has touched a surface, where only small amounts of DNA have been left behind, or only poor quality is found.

It is hoped 40 per cent more samples will be identified, leading to tens of thousands of "cold case" crimes, which have laid on file, being solved.

The Forensic Science Service's DNA manager, Paul Hackett, said: "This means a great many more cases have the potential to be solved and a great many more families could look forward to securing justice."

Operation Recall began two years ago and is still based in Bradford with a 12-strong investigation team using advanced DNA techniques to research unsolved rapes and murders throughout West Yorkshire.

Old scientific samples were re-examined to obtain DNA profiles which could pinpoint one person in a billion.

About 30 cases, going back to 1989, have been re-examined and half of those have been pursued, with successful convictions including that of Martin Done, 44, of Keighley, who was jailed for ten years earlier this year for the rape of a woman in her home in 1989. During the attack he threatened the victim's baby with a knife.

Det Supt Shaw said: "You look at cases like that of Done and the success of Operation Recall speaks for itself. People would never have been identified without us looking at cases from this new angle."

He said West Yorkshire detectives would be using DNAboost over the next few weeks to reassess a number of cases which the Operation Recall team had looked at unsuccessfully to see if forensic scientists could now progress them.

He said: "We will look at every case as a new case and see where it takes us.

"As long as the samples and swabs are kept, we can detect cases 20 years down the line. The message to people who have committed crimes long ago is that we are still looking for you and the new forensic techniques give us the opportunity to bring you to justice."

e-mail: steve.wright@bradford.newsquest.co.uk