Austin Stack, the son of a murdered Republic of Ireland prison officer, has confronted Gerry Adams over what he knows of his father's murder.
At a Sinn Fein Brexit event on Thursday Mr Stack branded Mr Adams a "disgrace" if he didn't name an IRA figure who had information over the murder.
He called on the Louth TD to tell gardai who was involved in the killing, adding "you have told your lies and untruths in the Dail."
In response Mr Adams said he completely rejected the claims made.
Former IRA gunrunner Martin Ferris and Provo bomb-maker Dessie Ellis were named in an email sent by their party leader to the Garda Commissioner as people who may have information about the killing.
Adams attempted to put the controversy to bed on Wednesday by making an unprecedented statement to the Dail in which he rejected suggestions of improper behaviour in relation to the Stack family’s attempts to establish the truth about their father’s murder in March 1983.
Brian Stack, chief prison officer at the high-security Portlaoise Prison, was murdered by the IRA in March 1983
He was was shot in the back of the neck after leaving a boxing contest at Dublin's National Stadium.
His sons had several meetings with Mr Adams in 2013 and in August that year they travelled in a blacked-out van to an undisclosed location along the border where a former Provo chief admitted the terror group was responsible for the murder.
The IRA said the killing was not sanctioned by the leadership of the organisation, but carried out by a renegade.