Jail chiefs are bracing themselves for a major report of a £30m Government investigation into the 1997 murder inside the Maze Prison of loyalist Billy Wright, one of Northern Ireland's most feared assassins.
It is due to be published this afternoon after Ulster Secretary Owen Paterson addresses the House of Commons and is expected to be highly critical of the prison service when Wright, 37, was ambushed by armed republican prisoners who managed to slip through security and open fire.
The murder, just two days after Christmas 1997, threatened to disrupt the tense all-party political negotiations in the months before the signing of the Good Friday Agreement the following year.
Wright, from Portadown, Co Armagh, leader of loyalist splinter group the Mid-Ulster-based Loyalist Volunteer Force (LVF), and allegedly linked to up to 20 murders of mostly innocent Catholics, was sitting in the back of a prison van waiting to be taken to meet his visiting girlfriend when he was shot seven times.
Three republican prisoners belonging to the Irish National Liberation Army (INLA), a republican breakaway faction, were involved.
Two of the three, Christopher "Crip" McWilliams and John Kennaway, had been transferred into the same H-Block as Wright the previous May, just weeks after Wright was moved from Maghaberry Prison, also near Lisburn, Co Antrim, to serve out an eight-year sentence.
The two men and a third man, John Glennon, armed with a semi-automatic pistol and a double-barrelled .22 Derringer, moved in to kill him after hearing his name announced over the prison Tannoy system.
They surrendered themselves to prison staff and were later sentenced to life imprisonment but released early under the terms of the 1998 peace deal.
At the time of Wright's murder, one of them told police: "Billy Wright was executed for one reason and for one reason only, and that was for directing and waging a campaign of terror against the nationalist people from his cell."
The inquiry was set up by the Government after investigations by retired Canadian judge Peter Corry into allegations of collusion by prison staff.