An organisation calling itself "the IRA" has claimed responsibility for the killing of prison officer, David Black.
In a statement issued to various media, the group said they had killed Mr Black because of conditions in Maghaberry Prison.
Mr Black, 52, died after his car was ambushed on the M1 in Co Armagh on 1 November.
He was on his way to work at the high-security prison when the attack was carried out.
Mr Black, from Cookstown, Co Tyrone, had worked for over 30 years in the prison service and was nearing retirement.