Files on unsolved crimes dating as far back as 1959 are to be reopened by police in South Yorkshire thanks to advances in DNA technology.
DNA is being taken from samples and checked against a database
A new team of detectives has been set up to re-examine dozens of so-called 'cold cases'. They will initially focus on sex crimes.
South Yorkshire Police has been testing a new system which can interpret previously unintelligible DNA samples.
The DNA is then checked to see if there are any matches on a national database.
Det Supt Richard Fewkes, who is leading the team, said: "Our work will be based on the materials and samples held by the Forensic Science Service (FSS), which go right back to 1959.
"Advancements in DNA and the introduction of the National DNA Database means we will be able to re-examine those cases in a renewed effort to trace the offender."
The team is working back in five-year blocks from 1992 and has already obtained full DNA profiles of offenders in four cases.
James Lloyd was traced through DNA from his sister
Samples from a further 10 cases between 1988 to 1992 are being studied by scientists.
Work on the second block from 1983 to 1988 is now taking place.
Mr Fewkes said: "We're liaising closely with our colleagues at the FSS and the Crown Prosecution Service to decide which cases to review and how they should progress.
"These cases all relate to serious sexual assaults, some committed by serial offenders.
"In all cases being reviewed, the offenders have gone unpunished and remain at large for very serious crimes.
"This new initiative will have a positive impact on public confidence and ensure justice is achieved for victims."
South Yorkshire Police famously used advances in DNA technology to catch the so-called Dearne Valley Shoe Rapist, James Lloyd, who terrorist women in Rotherham and Barnsley in the 1980s.
Lloyd, of Thurnscoe, South Yorkshire, was tracked down through his sister's DNA. He was jailed for life last year.