Ann Travers called on MLAs who know Mary McArdle, the woman jailed for her sister's murder in 1984, to ask her who else was involved in the killing, on 21 November 2012.
Ms Travers appeared before Stormont's finance committee to comment on a private member's bill being brought forward by the TUV's Jim Allister.
It aims to ban those convicted of an offence carrying a sentence of five years, or more, from holding the post of special adviser to a Stormont minister.
Mr Allister previously said he brought forward the bill following the appointment of Ms McArdle as special adviser to Culture Minister Caral Ni Chuilin.
Ms McArdle's appointment stirred controversy in 2011 when it was revealed she had been convicted for her part in the IRA murder of Mary Travers.
The 22-year-old was shot dead by an IRA gang as she left Mass with her father, the magistrate Tom Travers.
"I know that some of you today know Mary McArdle quite well. So I am pleading with you to speak with her today after this meeting and ask her who else was involved," Ann Travers said.
"This surely would be the greatest restorative justice of all."
Sinn Fein Mitchel McLaughlin said he wanted to respond to what he believed had been a question directed at him.
"There's only one way in which you can get a satisfactory answer to the truths that you are trying to uncover. It is when all parties to the conflict agree that they will contribute their truths as well," he said.
Ms Travers also said she wanted to make it clear that she had never said ex-prisoners were not entitled to work.
"In fact to the contrary, I feel quite strongly in rehabilitation and allowing truly remorseful ex-prisoners to move on with their lives. Mary McArdle has shown no remorse," she added.
Ms Travers said she had been "frozen" since she learned of Mary McArdle's appointment and that she and her family had had to revisit something "so dreadful".
She added that she believed the rights of victims had been forgotten about.
"For those who do not support this bill, I ask the simple question, do you believe the rights of perpetrators of violence are more important or supersede those of the victims in a civil society?"
In March 2012, Ms McArdle was replaced by Jarlath Kearney, a former journalist who had worked as a Sinn Fein policy advisor.
Academic human rights experts also spoke on the bill's compliance with human rights.
Their appearance at the committee came after the Attorney General, John Larkin, raised concerns that the retrospective nature of the bill could possibly infringe the European Convention on Human Rights.
He had earlier said article seven prohibited the increase of punishments available at the time an offence was committed, and questioned whether a disqualification might constitute such an increase.
However, Professor Brice Dickson from Queen's University said he did not believe the bill would fall foul of the convention.
"On the current law, my current estimation would be that there would not be a inconsistency or an incompatibility between what's proposed in the bill and the current interpretation of article seven given by the European Court of Human Rights," he said.
Chief human rights commissioner Professor Michael O'Flaherty said the European Court did not like dealing with civil service recruitment as it believed this was a matter for the state.
"The law is rather grey on what's before you," he said.
"To a very large extent, the law is not going to be able to tell you what to do. We are going to have to ask you, the politicians, to make the determination based on a review of the varying perspectives of the law, in the absence of clear court guidance across many of the questions you are exploring."