Old Bailey bomber Dolours Price, who fell out with Sinn Fein president Gerry Adams over the peace process, has been found dead at her home in north Dublin.
Price (62) was a republican hard-liner who became a bitter critic of Sinn Fein when the party endorsed the Good Friday Agreement and encouraged the IRA to give up its weapons.
She was at the centre of a transatlantic legal battle over an interview given to American university academics in which she implicated Mr Adams in the murder of a Catholic mother of 10 at the height of the Troubles.
Anthony McIntyre, a former IRA man turned historian, who helped coordinate the Boston College Belfast Project, said: “I am still in a state of shock by her death.
“These things come up on you and leave you devastated. She was a godmother to my son so there was a personal connection. It is a difficult time.”
The Belfast Project recordings were made more than a decade ago on the basis that they remain secret until the death of the 28 former republican and loyalist paramilitaries who took part.
Price claimed to have driven Jean McConville to the place of her death in 1972.
The west Belfast woman was among dozens of people, known as the Disappeared, who were abducted, killed and secretly buried by the IRA.
Price alleged that Mr Adams, now a Louth TD, was her IRA commanding officer during the early 1970s.
PSNI detectives reopened the investigation into Mrs McConville’s murder and in 2011 mounted a legal challenge to obtain transcripts of Price’s testimony.
Her death means that Boston College may now relinquish those tapes.
Mr McIntyre added: “I will have to talk to the solicitors. I am not sure what the situation is.”
Price’s father Albert was involved with the IRA and was interned by the Irish Government at the Curragh Camp during the 1950s.
Her 58-year-old sister Marian has been imprisoned in Northern Ireland since 2011 after her licence was revoked for her part in a dissident republican Easter rally.
In 1973 the two sisters and Sinn Fein MLA Gerry Kelly were part of the IRA unit that planted four car bombs outside the Old Bailey.
Two of the bombs exploded, injuring more than 200 people.
Dolours Price, who was sentenced to life for the explosion, accused Mr Adams of sanctioning the court attack.
Mr Adams has always denied ever being a member of the IRA.