Irish republican leader Gerry Adams received a "credible" death threat following his release after four days of questioning over a notorious IRA killing in Belfast.
The Police Service of Northern Ireland (PSNI) visited Adams's wife at their home on Sunday night to warn them of a "serious threat from criminals", his Sinn Fein party said.
Adams, who played a key role in the peace process in the troubled British province, was questioned by detectives for four days over the abduction and murder of mother-of-ten Jean McConville in 1972.
The Sinn Fein president strongly denies any involvement and was released on Sunday, although prosecutors are considering whether there is evidence to bring charges.
His arrest exposed tensions in the power-sharing government in Northern Ireland, where peace remains fragile 16 years after the Good Friday Agreement largely brought an end to three decades of sectarian conflict.
Adams was campaigning for the forthcoming European and local elections on Monday night, but he faced more trouble when one of McConville's children accused him of threatening him.
Michael McConville, who was 11 when he watched his mother dragged screaming from their home in Belfast, said Adams had warned him of a "backlash" if he ever revealed the names of those he witnessed taking her.
The Irish Republican Army (IRA) paramilitary group wrongly accused McConville of being an informer for the British army, but did not claim her murder until 1999. Her body, with a shot to the head, was found in 2003 on a beach.
In an interview with BBC radio, Michael McConville said he was "disappointed" that Adams had been released.
McConville says he fears even now that he would be shot if he disclosed the abductors' identities, but he said he told Adams a decade ago that he might name names.
Between 2004 and 2006, Adams brokered discussions between McConville and members of the IRA over whether the paramilitaries would apologise for his mother's murder.
When the IRA figures said they would not, McConville said he would release the names of those involved.
"Gerry Adams says to me, Michael... 'if you release the names I hope you are ready for the backlash'," McConville told the BBC.
"I took it as a threat... I think he meant by republican people and that's the way I took it."
However, Adams told CNN on Monday: "I never said that."
Prosecutors must now decide whether there is enough evidence to charge Adams, a decision that would send shockwaves across the troubled province.
His arrest on Wednesday night sparked a bitter row between Sinn Fein, who are committed to ending British control of Northern Ireland, and the pro-British Democratic Unionist Party (DUP) with whom they share power in Belfast.
