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 County Louth for more than 30 years until eventually located in 2003.
On the 10th anniversary of the recovery of her remains, relatives issued legal pro-ceedings 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 she had been abducted.
Ciaran Mulholland, lawyer for the children of Mrs McConville, 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."
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."