The 1984 murder of Mary Travers was a "tragic mistake", a woman convicted of the killing who is now a top Sinn Fein adviser has said.
Mary McArdle, 46, was part of an IRA gang who ambushed Tom Travers and his family as they left Mass in Belfast. Mary Travers, 22, was killed.
Miss Travers' sister Ann reacted with anger to Ms McArdle's Stormont job.
Ms McArdle told the Andersonstown News she did not believe anything she said could ease the family's grief.
In her first interview since being appointed as special adviser to Culture Minister Caral Ni Chuilin, she told the newspaper: "I want to state clearly that the killing of Mary Travers was a tragic mistake and I regret that it happened.
"If I were to begin to describe the specific context of conflict I would be accused of trying to justify her death, and I have no wish to do that."
She said she served 14 years in prison and was a fellow inmate alongside Ms Ni Chuilin.
"Since my release from prison I have been active in Sinn Fein and have played, I hope, a constructive and positive role in winning and maintaining support for the peace process within the nationalist and republican community, not least among the community where I live and which has suffered enormously from the past conflict - and that is what I intend to continue to do."
Mary Travers' sister Ann said last month she was shocked and felt physically sickened by the appointment.
"She's now (McArdle) in the position in which she is paid by the taxpayer - of which my mum is one," she added.
"I am absolutely horrified that she has been given such a position.
"I think it's really wrong and I think she should stand down."
The appointment was also criticised by First Minister Peter Robinson, who described the decision as "insensitive and a mistake".
However, the minister, Ms Ni Chuilin, defended the choice and said Northern Ireland was now in "a post-conflict environment".
"Myself and my special adviser are both former political prisoners.
"The Good Friday Agreement in 1998 recognised the role of political prisoners
"I understand that, particularly where families have been bereaved, there are huge issues around grief and I respect that."