Soham murder Ian Huntley has admitted to his parents that he deliberately killed Jessica Chapman, according to a report.
Huntley (30), who is serving life for the double child killings of Holly Wells and Jessica, made the shock confession during a prison visit by parents Kevin and Lynda, the Daily Mirrorsaid.
The parents have spent months trying to persuade their son to tell the truth over what happened to the 10-year-old school pals in his house in August 2002.
Mr Huntley told the newspaper they had now found out what happened to Jessica, but his son still needed to explain what happened to Holly.
Huntley admitting killing the two girls during his Old Bailey trial last year but claimed both deaths were an accident.
Police are to look in to the details obtained by the newspaper, the Mirror said.
Mr Kevin Huntley (49), told the newspaper: "We sat down with him and we're about 80% there.
"We've found out what happened to Jessica. We've spent months trying to persuade him to tell the truth.
"Those poor families deserve to know, we deserve to know, the whole country deserves to know."
Mr Huntley and his wife said to have talked with their son while he was at the top security Belmarsh prison in south-east London. He has since moved to Wakefield jail in west Yorkshire.