Edgar Graham, the Ulster Unionist Assembly member and Queen's law lecturer who was murdered by the IRA at point blank range. Picture Pacemaker Press

Peter Doran, 55, who has been selected to run in Lagan Valley, had recently expressed “profound sorrow” about Mr Graham’s death...as he deeply regretted all Troubles-related deaths.

However, Dr Doran stopped short of saying the killing of the unionist politician –who lectured at the same law department – was wrong. The News Letter pressed him on the matter yesterday but he did not speak.

Mr Graham, 29, was gunned down outside the university’s library on December 7 1983. He was shot several times in the back of the head by two gunmen who had been mingling with students.

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Sinn Fein Lagan Valley candidate Dr Peter Doran along with the party's leader in NI Michelle O'Neill

According to the book Lost Lives, six to eight shots were fired at the barrister and Ulster Unionist member of the Northern Ireland Assembly.

Two former Queen’s students were later given suspended jail terms for withholding information about the murder. The Provisional IRA said Mr Graham and his colleagues had “rejoiced in the assassinations of republicans, whether or not they were IRA volunteers or unarmed political activists”.

Asked by a journalist at the weekend to comment on the killing, Dr Doran said: “Anything a party candidate can say is never adequate. The first thing you think of is the dignity of the family,”

Sinn Fein Lagan Valley candidate Dr Peter Doran along with the party's leader in NI Michelle O'Neill

During the course of the Belfast Telegraph interview, he added: “The conflict invaded the lives of many people. The tragedy of the conflict and all the tragic choices that people made at that time including the life and the family of Edgar Graham, that is a matter of profound sorrow to me, of course.”

In response to Dr Doran’s comments, Trevor Ringland writing in the News Letter on Tuesday challenged Dr Doran and Sinn Fein’s Northern Ireland leader Michelle O’Neill to “make it clear not only that the murder was regrettable, but, more importantly, whether they consider it unjustified”.

Mr Ringland, who is a solicitor and former co-chair of NI Conservatives, said that if the pair were prepared to “not to insist that IRA violence was necessary” then a break with the past was possible.

Mr Ringland said: “Edgar Graham was a young man with tremendous potential, who was a rising star in the Ulster Unionist Party. He was killed because the republican movement saw that he would be a future leader of constructive unionism.”

Dr Doran is standing in the Lagan Valley constituency where Sinn Fein’s fortunes have waned since Paul Butler last held a seat in 2011.

The life-long environment campaigner was previously involved with the Green Party in Upper Bann before joining Sinn Fein. A former journalist with the Derry Journal, Dr Doran said he always wanted to remain involved in politics.

Having served his time as a back room activist for Sinn Fein – contributing to policy development – claims to have “provided input into lots of research over the years.”

Mr Ringland went on to say: “It is inadequate for a member of the republican movement to express remorse over Edgar Graham’s murder. A true democrat should be unequivocal in stating that it was unjustified.

“I await clarification from Dr Doran and his new leader. Is Sinn Fein genuinely becoming a political party or is it a front for the IRA masquerading as democrats?”