Fianna Fáil TD and former Government minister Dr Jim McDaid has said he believes it is likely that cattle-dealer Richie Barron was beaten to death, despite the fact that the Morris tribunal has found it to be a hit-and-run accident.
His comments have led to him becoming embroiled in a row with the McBrearty family, who have accused him of endangering their safety by his comments.
Dr McDaid told The Irish Times he did not understand why the McBreartys had criticised him as he was making no suggestion about them and accepted they were not involved in any way in Mr Barron's death.
The TD, who lives in Letterkenny and whose constituency covers Raphoe, said he had visited the scene of Mr Barron's death and believed it was almost impossible for a car to have been travelling at a sufficient speed to have caused the injuries to Mr Barron.
He said he had read the different pathology reports on the death, which differed from each other, and failed to come to a definitive conclusion about the exact cause of death. "They state there is a possibility he was killed in a motor-vehicle accident, and a 'probability' he was killed in an assault," Dr McDaid said.
Dr McDaid said he believed the likelihood was that he died following an assault as opposed to a hit-and-run, and that there were people in Donegal who know what happened.
"It's not just one person that knows, but two, three, four or five people who know what happened to Richie Barron."
Dr McDaid denied his comments were motivated by the fact he was personally acquainted with many of the gardaí criticised in the second Morris report, but that the whole truth in relation to the incident had to emerge.
"What I'm saying is if this county is to come to terms with all of this, well, then every line of inquiry will have to be followed."
Dr McDaid, who also spoke about his reservations regarding the Morris report to the Donegal Democrat and Highland Radio, accepted he could be criticised for failing to raise the issue of Garda corruption during the 1990s, but said he had accepted the account from Garda authorities at the time that an investigation into Mr Barron's death was ongoing.
His comments have enraged the McBrearty family, however, and yesterday Frank McBrearty jnr challenged Dr McDaid to "put up or shut up" on Highland Radio and suggested the comments could endanger his family.
Mr McBrearty told Dr McDaid he had contacted the Taoiseach's Office and was asking for "Fianna Fáil to expel you from the Fianna Fáil party because you're a disgrace".
Dr McDaid's comments were described as "scandalous" by Fine Gael MEP Jim Higgins, who was centrally involved in raising concerns about Garda corruption in Donegal in the late 1990s as his party's Dáil spokesman on justice.