An IRA unit that conducted an investigation into the murder of a German backpacker could hold vital clues about her killer.
The dramatic revelation has led to a fresh plea for information to bring the murderer of Munich teenager Inga Maria Hauser to justice.
No one has been convicted over the death of the 18-year-old in 1988.
However, the Provos considered passing information about the alleged murderer to the RUC at the height of the Troubles, it has been claimed.
A source said: "They had identified somebody that was responsible from the Loughgiel area and we believe they had a debate amongst themselves about whether that information should be passed in one way or another to the police."
Last night an MLA who has campaigned for justice for Inga Maria urged anyone with information to "do the decent thing" and end her still-grieving family's pain.
John Dallat said: "It is heartbreaking to think that anyone with knowledge of Inga Maria's murder would keep it for 30 years, depriving her family of closure.
"Inga Maria was a totally non-political, innocent young girl who lost her life defending her honour from a monster.
"Anyone with any information must talk immediately to the detectives, because they won't be able to live with the guilt much longer."
The teenager's case remains among the most high-profile unsolved murders in Northern Ireland.
Her body was found dumped in a remote part of Ballypatrick Forest outside Ballycastle, Co Antrim, 14 days after she was last seen alive on a ferry from Scotland.
Detectives believe a number of people may have been involved either directly or in the cover-up, and have previously said they only need fractional pieces of evidence to bring the chief suspect or suspects to justice.
A man in the rural area east of Ballymoney in Co Antrim was seen soon after the murder with scratches on his face, sparking rumours in the community that he had been involved.
It is understood at least one of those involved in the IRA's clandestine investigation may have passed away.
But the source added: "There may well be other people who were privileged to the debate that was held.
"We are now 30 years down the line. A lot of things have changed. A lot of water has gone under the bridge.
"These people may still have that knowledge. That debate indicates that they wanted this resolved.
"The fact that they were debating it in 1988 highlights that they thought this was something different."
Police have a male DNA profile from the crime scene, but have yet to secure a positive match.
A number of years ago, in one of the largest DNA screenings ever undertaken in the UK, 2,000 samples failed to produce a definitive match to the evidence found at the scene.
However, officers have recently conducted further testing, including a trawl of updated familial DNA samples.
Detective Chief Superintendent Raymond Murray, the officer leading the investigation, said: "We have been aware of this account of events for some time and I would reiterate my appeal for anyone with information to come forward.
"It is not too late to tell us what you know."
Prior to her death, Ms Hauser had travelled through England and Scotland and, according to diary entries, intended to travel south to Dublin when she docked at Larne.
But for reasons as yet unexplained she ended up going in the opposite direction, and tragically met her killer.
Mr Murray added: "Inga Maria's family deserve to know what happened, deserve closure after 30 years.
"Her father died not knowing who killed his daughter and her mother has been ill for many years. The family have been tortured by her murder and we have been in close contact with Inga's heartbroken sister in the run-up to this anniversary."
Addressing the killer, he added: "Do the decent thing for Inga's sister and mother.
"What if this was your daughter or granddaughter - subjected to a brutal and ruthless assault after arriving in a new country before being killed and left in a forest. Think of the fear and pain she felt, think of her family not having justice.
"After 30 years, it's time to tell us what you know."
Last month a 30th anniversary memorial service was held in Ballypatrick Forest and an inscription stone unveiled by Mr Dallat and singer Keeley Moss, who have campaigned for justice for Inga Maria.
Mr Dallat added: "The roses at Inga Maria's memorial stone in Ballypatrick Forest are fading but they are being replaced with fresh flowers and a renewed determination to see justice for this young girl."