A man imprisoned for 42 years for one of the Cannock Chase murders is applying for a judicial review to allow him to challenge his conviction.
Raymond Morris, 81, from Walsall, was found guilty of murdering Christine Darby, seven, who went missing in 1967.
She was one of three girls living near the A34 whose bodies were found buried in Cannock Chase, Staffordshire.
Diane Tift, five, and Margaret Reynolds, six, went missing in 1965 but no-one was charged with their murder.
All three had been abducted from the streets of the West Midlands and had been raped and murdered before being dumped at the beauty spot.
The investigation that followed was one of the biggest in British criminal history.
Morris was convicted of Christine's murder in 1969 but his solicitors Norrie Waite & Slater said there were flaws in Staffordshire Police's handling of the original investigation and evidence.
On that basis they said he had applied to the Criminal Cases Review Commission (CCRC) in 2003 to refer the case back to the Court of Appeal.
The CCRC, a statutory body that investigates the safety of criminal convictions, said in June the case should not be referred to the Court of Appeal.
Morris' solicitors claims the CCRC's own investigation experts said they were concerned about the safety of his conviction.
They said Morris was now seeking a judicial review of the CCRC's non-referral decision.
His solicitor Amy-Jo Cutts said: "My primary objective is not to sully anybody's name. Our primary objective is to get justice.
"We are fully aware of the tragedy of this case which must still be very raw in Walsall.
"But potentially the murderer is at liberty, which is something we feel needs to be looked at."
Leeds Administrative Court said the judicial review was listed for December but no specific date had been given for a hearing.
Staffordshire Police has yet to comment.