POLICE are re-examining the most serious unsolved rapes and sex crimes from the past 30 years.

Lancashire Police’s Cold Case team is looking at 25 historic cases, some of which date back to the 1970s.

Detectives won’t reveal details of which cases are under review but say the team, made up of four officers and one researcher, is also investigating 15 unsolved murders dating back to the 1970s.

Advances in technology mean police can now put together DNA profiles of attackers from samples taken at crime scenes, which they were unable to do so at the time.

These are loaded on to the national DNA database and checked against the records of 183,000 people.

This system has lead to a string of breakthroughs and significant convictions in the past four years.

Last year, Leslie Robert Marshall, 51, from Scotland, was jailed for the so-called ‘silent rape’ of a Burnley woman in January 1989.

Graham Darbyshire had escaped detection for 11 years after committing one of Lancashire’s most brutal rapes in Witton Park.

Cold-case officers could not match the DNA with anyone on the database, so they searched for possible relatives of the attacker, which led to Darbyshire’s arrest and conviction in 2006.

Similarly, Polish immigrant Silvester Kisielinicki, 26, was cleared of a minor auto crime in 2007 – but DNA taken at the time of his arrest was held on the national database and used to convict him of the rape of a woman in Montague Street, Blackburn, a few months later.

To prevent raising a victim’s hopes unnecessarily, the team won’t contact them until it has identified the offender.