Lawyers for a Kent man who has fought a murder conviction for nearly 50 years have claimed papers from 1992 and 2001 were not disclosed at a 2002 appeal.
Paul Cleeland has made a fresh request to the Criminal Cases Review Commission (CCRC) to revisit his case.
He served 26 years for the murder of Terry Clarke in Hertfordshire in 1972.
The claims were made during a judicial review bid but a judge said they should be dealt with separately. The CCRC said it would consider the application.
Suspected gangland boss Mr Clarke was shot in Stevenage after returning home from a bar on 5 November. Cleeland, of Folkestone, insisted he was at home with his wife when Mr Clarke was killed.
During the judicial review bid, Cleeland's legal team claimed retired judge John May received evidence on the case as early as 1992 as part of the Royal Commission on Criminal Justice (RCCJ) - an inquiry that followed a series of high-profile miscarriages of justice including the Birmingham Six.
Edward Fitzgerald QC, Cleeland's barrister, also said the CCRC investigated the work of forensic Scotland Yard firearms expert John McCafferty on Cleeland's case in 2001.
He wrote neither development was disclosed to the Appeal Court in 2002, when Cleeland's second appeal failed.
Mr Justice Lavender said the new allegations could be dealt with more expeditiously if Cleeland either issued a separate application, or invited the CCRC to take a decision in light of the claims.
Cleeland is seeking a judicial review of a decision by the CCRC not to refer his case to appeal.
The CCRC said it could not comment on the judicial review proceedings, but a CCRC spokesman said: "We can confirm that we have recently received a further application from Mr Cleeland.
"We will consider this application in due course and determine whether it raises anything new that is relevant to the safety of Mr Cleeland's conviction."
Cleeland's solicitor Ricky Arora urged the CCRC to expedite the application. He told them Cleeland was now 79 and of "failing health".
Inquiries have been made by Cleeland's MP Damian Collins, the Home Office and the BBC about archives on the case.
The BBC has accessed several files under freedom of information from Sir John May's RCCJ archive, at The National Archives. However, it has not been possible to view them during coronavirus lockdown and the BBC has not yet established what they contain.
Mr Collins submitted a series of written questions to the Home Secretary and was told the Home Office is reviewing what material exists.
The CCRC confirmed it also held an archive on Cleeland. Home Office minister Kit Malthouse said the CCRC files were being transferred to the department and examined.