The family of a mother of 10 murdered and secretly buried by the IRA is to sue the security forces over alleged failures in the handling of the case.
Jean McConville, 38, was abducted by paramilitaries in west Belfast in 1972 and interrogated on suspicion of being an informant.
Killed and subsequently buried by her captors across the Irish border, her remains lay undiscovered beneath a beach in Co Louth for more than 30 years until they were eventually located in 2003.
On the 10th anniversary of the recovery of her remains, relatives issued legal proceedings against Police Service of Northern Ireland Chief Constable Matt Baggott and the Ministry of Defence over the initial investigation into her kidnapping and the handling of the controversial case ever since.
They claim the then Royal Ulster Constabulary failed to act on reports that she had been abducted.
Lawyer for the children of Mrs McConville, Ciaran Mulholland said: "Unfortunately the McConville family continue to mourn and grieve at the loss of their mother because they remain in the dark, their questions remain unanswered.
"The family still do not know the circumstances of this horrendous event - why was their mother taken? Why would the RUC not intervene or investigate the matter?
"The McConville family firmly believe that the RUC and subsequently the PSNI have utterly failed to assist the family's quest for the truth. It is abundantly clear that police negligently failed to hold a prompt and efficient investigation into this matter.
"The family now feel that given the lengthy passage of time and the obstruction they continue to meet seeking the truth into the disappearance and murder of their mother that they have no alternative other than to hold the police and Ministry of Defence to account.
"Our clients' feel that legal action is now essential in their journey for truth, and accordingly representations have been sent to both the Chief Constable and the Ministry of Defence."
Family members claim that their mother was first taken by the Provisional IRA on November, 30 1972 from a bingo hall in the lower Falls area of Belfast and interrogated on suspicion of being an informant.
They said she was found by an Army patrol in the early hours of December 1 "roaming the streets in a state" and taken to Queen Street RUC station in the city.
Relatives further recall that later that day, around 6pm, Mrs McConville was abducted again by members of the IRA.
Mr Mulholland claimed: "This was reported to the RUC at Queen Street within hours, however police refused to assist. This was again reported to police daily throughout the months of December and January; however police still failed to act. It is believed that the deceased was tortured and murdered by the PIRA on or around December 1972. "
A spokesman for the Police Service of Northern Ireland said: "As this is a legal matter it would be inappropriate for us to comment."
An MoD spokesman said: "The MoD has and will continue to co-operate fully with all judicial processes. It would be inappropriate to comment further due to the on-going civil police investigation."