A DUP MP will tomorrow name a senior Sinn Fein member he believes was a British agent involved in the murder of his cousin.
David Simpson MP has secured a slot in the timetable of the House of Commons to name the republican tomorrow evening at around 7pm in a debate on Northern Ireland policing.
As an MP Mr Simpson is able to use Parliamentary privilege to name the individual, which affords him complete protection from any possible legal action by the accused.
"There are serious questions that surround the individual concerned," said Mr Simpson.
"Did they pass on all that they knew to the security forces or only a portion of it? Did they stand to one side and allow other terrorist operations to take place when they may have been able to prevent them? Did their role as an informer protect them from any potential prosecutions?"
"These questions deserve answers. I hope that by bringing matters to the fore some answers may be forthcoming."
The killing was that of Mr Simpson's cousin, father-of-two Frederick 'Eric' Lutton, 40, a former RUC reservist shot dead on May 1, 1979, near Moy in Co Armagh.
The IRA claimed responsibility for killing the National Trust caretaker but no one has ever faced charges.
Earlier this year Mr Lutton's moving recollections of the last Twelfth he spent with his father recently won a News Letter short story competition.
Two years ago Sinn Fein's Denis Donaldson was exposed as a police agent and later shot dead in Donegal.
The unveiling of such a senior agent caused widespread paranoia among republicans and the subsequent killing infuriated unionists, who saw it as continued PIRA activity.