New Bill inspired by Jack's dabs

Mr Straw said new proposals to allow the police to keep fingerprints and DNA samples from volunteers and suspects acquitted of crimes come from his own experience.

The Home Secretary was special adviser to his predecessor Barbara Castle, when she was Social Security Secretary in April 1976, when some sensitive Cabinet papers were leaked to the Press.

Prime Minister Harold Wilson ordered a Whitehall inquiry to find the culprit.

All relevant officials were asked to volunteer fingerprints, and the young Mr Straw happily did so. When the investigation was over and he had been cleared, the police returned him his fingerprints.

He told them that they could keep them, but they said that under the law they had to be returned to the individual or be destroyed.

Mr Straw said: "I thought at the time this was ridiculous. They obviously could be useful in future, but they couldn't allow me to consent to them retaining them."

Now, as Home Secretary, he is to change the law on the issue as part of his Criminal Justice and Police Bill.

In future when as part of a criminal investigation police lawfully take ordinary fingerprints or DNA samples, they will be able to retain them and file them on a database with or without the consent of the suspect.

Where people volunteer such samples as part of a sweep to eliminate suspects, such as in the case of a serial rapist, the police will be able to retain them with the written consent of the individual.

Mr Straw said: "It's partly my experience and partly the fact that I have had cases where people have had to give samples more than once because the original ones were destroyed after an initial investigation failed and there was a second."

"There was one case in the East Midlands where people had to give three separate samples because each one was destroyed after each inquiry. It seems more sensible to be able to keep them to save costs and police time."