Sinn Féin president Gerry Adams said jailing the IRA killers of Tom Oliver would be "totally and absolutely counterproductive".
Mr Adams said he disagreed with the views of Mr Oliver's family that those who murdered him in 1991 should be put in jail.
Mr Oliver (42), a father of seven from Riverstown, Co Louth, was abducted and murdered by the Provisional IRA. His body was found on July 19th, 1991 in South Armagh. He was shot in the head.
The IRA claimed he had been a garda informer - a claim the Oliver family denies.
Nobody has ever been convicted of the crime, but gardaí launched a new investigation this year into his murder.
Mr Adams was asked if the killers of Mr Oliver should be jailed or let go free under the terms of the Good Friday Agreement.
He said families were “fully entitled” to seek prosecutions but he did not believe it would facilitate the peace process.
"At the same time filling the prisons again, putting people back into prison, I don't think it would be productive," he told LMFM northeast radio presenter Michael Reade.
When asked if he considered Mr Oliver’s death as murder, Mr Adams described it as a “politically motivated killing” and that, while he disagreed with some actions by the IRA during the Troubles, he agreed with the “general legitimacy of the armed response”.
He said Sinn Féin has “no information” about the circumstances surrounding Mr Oliver’s death.
“The IRA killed the man. The IRA gave their reasons for killing the man. That’s the historical record,” he said.
“I have no information whatsoever. My information on this is what I read about at that time.”
Stack family
Mr Adams also said he would not use his contacts with the IRA to help in the investigation into Tom Oliver’s murder because of his experience with the Stack family.
In 2013 he took two sons of Brian Stack, a prison officer murdered by the IRA in 1983, to meet a senior IRA commander. According to Mr Adams at the time, the commander told Austin and Oliver Stack that the men who killed their father was known to him and the perpetrators were still alive.
However, the issues was raised at the general election in 2016 when Mr Adams said Austin Stack had given him names as to who he believed killed his father.
Mr Adams said he provided the same names to the gardaí, but Mr Stack said he provided him with no such names.
Speaking on the LMFM programme, Mr Adams said the intervention on the part of the Stack family had “ended very badly”.
“I made it very clear that my ability to assist the families of victims was severely undercut by the way that whole initiative played out,” he said.
“I’m not going down the road that I have been down before which was exploited greviously by Sinn Féin political opponents which jeapordised any authority or influence that I may have within the broad republican constituency.”
Following his LMFM interview, Austin Stack accused Mr Adams of disrespecting the victims of IRA violence and lying.
He described Mr Adams’ comments as “outrageous” and showing utter contempt for the Oliver family.
Mr Stack said he had it on “good authority” that, contrary to what Mr Adams’ contacts had suggested to him, the IRA army council did sanction the murder of his father.
“The process we had with him fell apart because he told us lies,” he said. “He broke the trust about our meetings. I didn’t give him any names. That is where the process fell apart.”
