Pressure is increasing on Humberside police following the force's admission that it destroyed critical information on murderer Ian Huntley.
Huntley has begun two life sentences for the murders
The information about rape allegations was destroyed as the force believed it had to delete it under the Data Protection Act.
However, both the country's top officer and the Information Commission have criticised Humberside's actions.
Huntley was convicted of murdering Holly Wells and Jessica Chapman.
Humberside police investigated Huntley over three allegations of rape, an alleged indecent
assault on an 11-year-old and other accusations of unlawful sex with underage
The information was not highlighted when Huntley applied for a caretaker's job at a Soham school.
Chief Constable David Westwood said the information was deleted because none of it led to convictions.
His actions have been criticised by other police, including Scotland Yard Commissioner Sir John Stevens.
"With the Data Protection Act you have to push it to the nth degree," he said.
"The policy here is to hold on to things as long as we can - if someone's
being investigated for rape and there is a possibility they're a murderer, we
have a duty to hold on to that.
"We have to think about the public interest and that the public interest is
The independent information watchdog said the fault was with police, rather than the Act.
Assistant information commissioner David Smith said the Huntley decision "defied common sense".
"There are many difficult judgements to be made by the police in this area, but the information they had on Huntley did not come close to making it a difficult decision."
Home Office minister Hazel Blears said in a Commons statement on Thursday that police forces must have better systems for inputting arrest and conviction details.
She said a year-long study of forces' performance was "not encouraging", but that new practices had been put in place to overcome failings.
Home Secretary David Blunkett has ordered an inquiry into the effectiveness of intelligence and vetting used by the Cambridgeshire and Humberside forces to examine Huntley's background.
The police and social services are also carrying out investigations into their respective roles in the case.
Meanwhile, Huntley's mother reportedly wants her son to be put to death because of his horrific crimes.
Lynda Nixon told the Sun that her son's actions were "unforgivable" and he should pay for them with his own life.
Ms Nixon, 49, also said she had thought Huntley was guilty because she "saw it in his eyes" when he was arrested.
Ms Nixon told the paper: "I truly wish we had capital punishment.
"I believe Ian should not live after what he's done."
His former girlfriend, Maxine Carr, 26, was given three-and-a-half years for conspiring to pervert the course of justice but cleared of two counts of assisting an offender.