DEPUTY First Minister Martin McGuinness has again insisted he had no involvement in the murder of an IRA informer three decades ago.
Derry man Frank Hegarty was shot in head and his body dumped on the Tyrone-Donegal border in 1986.
His son Ryan, who was five at the time, has said Mr McGuinness "needs to tell the police what he knows".
However, the Sinn Féin veteran said he "had absolutely no role in the death of Frank Hegarty", whose murder is to be re-investigated as part of a major police inquiry into the activities of British army agent Stakeknife.
Ryan Hegarty told BBC's Spotlight programme that in the IRA's eyes his father committed the "ultimate crime" but to him he "saved the lives of human beings".
"It was terrible living in Derry as Frank Hegarty's son," he said. "He was known as a tout."
Mr McGuinness has always said that he advised Mr Hegarty's family that he should not meet the IRA if he was an informer.
The Spotlight programme featured recordings of Freddie Scappaticci, the man widely believed to be the agent Stakeknife, linking the deputy first minister to the 1986 killing.
TUV leader Jim Allister said Mr Hegarty's murder demanded "relentless investigation".
"The recording of Scappaticci puts McGuinness centre stage when it comes, as it must, to any investigation into how Frank Hegarty met his end," he said.
"Who colluded in having Frank Hegarty murdered is a key question which must have no boundaries and no untouchables if any investigation is to be credible."
Mr McGuinness said he was an elected representative at the time did what he could to assist the family.
"There are questions to be answered in relation to Mr Hegarty's death by those with detailed knowledge of this event, including British intelligence."
