West Yorkshire Police are reviewing offences as far back as 1974 as part of the cold case operation.

The massive scale of the investigations emerged as a rapist from more than 20 years ago finally admitted his crime at Leeds Crown Court after a DNA genetic sample match. Thomas Madigan was jailed for six years yesterday.

Last night the detective who led the team that trapped Madigan said the net was closing in on thousands of criminals who believed they had escaped the law.

Det Supt Colin Prime, head of Operation Recall, said: "The public can be assured that where crimes have been committed we will continue to review the files over and over again if necessary in the light of advances in scientific techniques.

"We are looking at 1,700 historic serious sex offences and I think those responsible should be very worried.

"The technology we have at our fingertips right now is incredible – and who can say what other technology may be around the corner in another two years time?

"There may well be no hiding place for criminals in future."

Madigan's victim, whom he raped in her own home, was so traumatised by knowing that her attacker was still as large that she moved house. She has not been able to trust men since.

Leeds Crown Court heard yesterday that Madigan was among the suspects at the time but gave an alibi and the case remained unsolved.

At the time of the attack on November 1, 1987, his victim had just returned home in the early hours after celebrating her 49th birthday with friends.

Her dog had run outside as she entered the terraced house in Huddersfield and she left her back door open for it to return. She then went into the living room and took some of her jewellery off.

But as she returned to call in the dog she was confronted by Madigan. He punched her in the face and raped her before fleeing the scene.

Michelle Colborne, prosecuting, told the court swabs taken at the time showed semen, and slides prepared from them were retained in cold storage at the Forensic Science Service Laboratory at Wetherby.

Following new checks last year Madigan's DNA was found to match. When questioned he accepted that at the time he was a burglar and had raided a house in the street where the victim lived, but he denied committing offences that night or being the rapist.

But yesterday Madigan, 48, of Blackmoorfoot Road, Crosland Moor, Huddersfield, pleaded guilty to rape. His lawyer indicated he did not want his victim to have to relive her ordeal.

Jailing Madigan for six years, Judge Shaun Spencer QC told him his past had finally caught up with him.

After the case, forensic scientist Cathy Turner said: "DNA technology was in its infancy when Madigan committed his crime, but the enormous strides forward in this field...have helped to finally bring him to justice.

"We will continue to work with West Yorkshire's Cold Case Unit to ensure that other offenders, who think they have got away with their crimes, are brought before the courts."