Sinn Fein leader Gerry Adams has been arrested by Northern Ireland police over the 1972 murder of Jean McConville.
Adams was taken into police custody for questioning last night.
In a statement from the party, Mr Adams told the Police Service of Northern Ireland (PSNI) he was available to meet about the case.
He said: "Last month I said that I was available to meet the PSNI about the Jean McConville case. While I have concerns about the timing, I am voluntarily meeting with the PSNI this evening. As a republican leader I have never shirked my responsibility to build the peace. This includes dealing with the difficult issue of victims and their families."
McConville, a widowed mother of ten, was abducted from her home in 1972 by 12 IRA gunmen, both men and women. She was driven across the border with southern Ireland by Dolours Price.
The 37-year-old was shot in the back of the head and her body was buried 50 miles from her home on a beach in the Republic of Ireland.
The IRA did not admit to carrying out her murder until 1999 and her remains were not discovered until August 2003 on Shelling Hill beach in Co Louth.
The terror organisation claimed McConville was an informer who was passing information about IRA activities in the area around the notorious Divis Flats in West Belfast.
Her family always denied the claims and an investigation by the Northern Ireland Police Ombudsman later rejected any claims that she was an informer.
It was Dolours Price's death last year that led the Northern Ireland Police Service to a series of taped recordings, concerning a group of 15 people who were abducted by the IRA and killed, who were known as 'the disappeared.'
They tapes documenting details of 30 years of Ulster's political strife were stored at Boston College in the US.
The American college had been archiving the interviews and had agreed not to make their contents public until each interviewee had died.
The contents of the tapes were revealed after the FBI, on behalf of the Police Service of Northern Ireland (PSNI), applied to US courts to have the tapes handed over last year.
In a series of exclusive interviews conducted at her home in Malahide, north Dublin, Price admitted she had been the person 'ordered' to drive Mrs McConville to meet her fateful end.
Price was part of a small, select unit of IRA members within the three battalions that made up the Belfast Brigade in the 1970's.
The group of eight hand-picked volunteers were nicknamed 'the Unknowns' and responsible for 'special operations', including internal investigations to weed out suspected informers, often employing brutal methods.
The IRA woman said she had received her orders from Adams, who was then her IRA commander.
She recalled: 'I had a call one night and Adams was in a house down the Falls Road and she'd (McConville) been arrested and held for a couple of days. She got into my car and as far as she was concerned she was being taken away by the Legion of Mary to a place of safety.
Price said of her part in the abduction of Mrs McConville: "I drove Jean McConville, a very, very unpleasant person. I know I shouldn't speak ill of the dead and I don't think she deserved to die, and at the time, I didn't know she had children.
"It wasn't my decision to disappear her, thank God. All I had to do was drive her from Belfast to Dundalk," she explained in the tapes.
She added: "I gave my testimony to the College and there's no way I'm going to agree to making it public because that would be helping those I've spent a lifetime fighting against. That would make me little more than an informer and no matter how much I despise that man (Gerry Adams), there's no way I'll volunteer any information to the police. What I will say is that after my death, I will come back to haunt Gerry, of that he can be sure."
Price's former friendship with Adams soured and her later contempt for him was evident as she said: "Gerry, the man who sold us all out, with the Good Friday agreement and by denying alongside some very brave men and woman. I can never forgive that."
Adams, now a Sinn Fein member of the southern Irish parliament, is an MP for Louth. He has always denied being a member of the IRA.
A second man, former IRA Chief of Staff in the North, Ivor Bell, now 77, has also been charged with aiding and abetting in the murder of Mrs McConville.