The antheral serving beingness for the execution of schoolgirl Milly Dowler has made a caller confession implicit the deaths of a parent and daughter, his lawyer said.
Levi Bellfield made a connection past twelvemonth successful which helium admitted killing Lin Russell and her girl Megan successful Kent successful 1996, but helium aboriginal retracted it.
His lawyer said helium has present made a caller signed statement, saying helium "needs to instrumentality responsibility".
Michael Stone was jailed successful 2001 for beingness for the murders.
Stone has ever protested his innocence implicit the attacks, and of trying to execution Megan's sister Josie.
In 2017 his ineligible squad said they had seen grounds of a afloat confession by Bellfield, thing helium denied astatine the time.
Theresa Clark, Bellfield's solicitor, said the caller confession is much detailed, manus written and signed by him.
Ms Clark said Bellfield's latest confession has been made aft helium engaged with situation psychologists.
"At the extremity of the day, the acquisition from my lawsuit is clear," she told the BBC. "He's adamant that helium did it.
"My lawsuit says, 'I did it, I request to instrumentality work for what I've done.'"
Ms Clark said Bellfield wanted relatives of those who were killed to person "resolution".
"He's not doing this due to the fact that he's affable with Stone, it's much for the families and Josie Russell," she added.
She said the confession has been passed to the Criminal Cases Review Commission.
The CCRC and Stone's representatives person been approached for remark by the BBC.
Lin Russell and her daughters Megan, past six, and Josie, nine, were attacked arsenic they walked on a state lane successful Chillenden, earlier being bound, blindfolded and bludgeoned with a claw hammer.
On the time of the murders, Dr Shaun Russell was told that helium had mislaid his full family. It was lone erstwhile an serviceman astatine the country noticed Josie determination they realised she had survived the attack.
Stone was archetypal recovered blameworthy of 2 counts of execution and 1 of attempted execution successful 1998 and again successful 2001, aft the Court of Appeal quashed his condemnation owed to doubts implicit a prosecution witness.
Bellfield is presently serving a beingness condemnation for the execution of 13-year-old Milly, who went missing from Walton-on-Thames, Surrey, successful 2002.
He has besides been convicted of murdering Marsha McDonnell and Amelie Delagrange, and of the attempted execution of Kate Sheedy, and volition ne'er beryllium considered for parole.
Det Chief Supt Lucy Morris, from the Kent and Essex Serious Crime Directorate, said: "Following 2 trials astatine which helium was recovered blameworthy by a assemblage connected some occasions, and an entreaty to the High Court, Michael Stone remains convicted of the murders of Lin and Megan Russell and the attempted execution of Josie Russell successful 1996.
"Stone made an exertion to use for a Judicial Review successful respect of his condemnation successful September 2012. The Honourable Mr Justice Blake ordered that support for the exertion should beryllium refused.
"The Criminal Cases Review Commission commenced an extended re-examination of the execution probe successful 2017 and has had entree to each forensic evidence, documentation and exhibits from the archetypal investigation, the reappraisal by Hampshire Police, details of the 2 Crown Court trials and appeals to the High Court."