A daughter of IRA murder victim Jean McConville has instructed a top London law firm to look at launching a civil suit against Sinn Fein leader Gerry Adams.
Mother-of-10 Mrs McConville was dragged from her Divis flats home in 1972 by the IRA. She was interrogated before being shot and buried.
She became one of the Disappeared, and the 37-year-old's remains were found on a beach in Co Louth in 2003.
This week the Public Prosecution Service (PPS) said there was insufficient evidence to consider a criminal legal action against Sinn Fein president Mr Adams, the party's northern chairman Bobby Storey and five others. Mr Adams has always denied any involvement.
Mrs McConville's daughter Helen McKendry said she had been left to take a civil action as a last resort to get to the truth.
She told the Belfast Telegraph: "For the sake of myself, my children and my grandchildren, I just want to get to the bottom of what happened to my mother.
"We waited 31 years to get my mother's body. We can't wait that long for the truth and justice - I'll not be about for that.
"There are people who know what happened, but they won't speak. To this day I believe Gerry Adams knows what happened to my mother."
A spokesman for McCue and Partners Lawyers, which won a multi-million pound landmark civil case against the Omagh bombers, said: "The family have waited patiently for the DPP decision. They now wish to determine whether other judicial avenues are open to them to secure justice and accountability for Jean's murder."
Mrs McKendry added: "There were a lot of lies surrounding the murder of my mother and that all needs to be cleared up for the sake of my family, we are all getting on in years. I can only hope this legal action will get us some justice."
Mr Adams said the PPS decision this week was long overdue.
"There was never any real basis for questioning me in respect of this case," he said after Wednesday's announcement.
"I played no act or part in Jean McConville's death. I support the PSNI. But the timing of my arrest showed there remain elements within the PSNI who are against Sinn Fein. But they will not succeed."
Mr Adams was arrested in relation to the case last May.