First Minister Arlene Foster has slammed a Sinn Fein MLA who paid tribute to the man who she believes tried to murder her father.
Sean Lynch posted a message marking the birthday of his "friend", the IRA man Seamus McElwain.
McElwain was shot dead by the SAS in 1986 as he and Lynch tried to ambush an Army patrol near Roslea, Co Fermanagh.
Yesterday the Fermanagh-South Tyrone MLA took to his Twitter page to remember his "comrade".
He wrote: "Remembering my friend and comrade Vol Seamus Mc Elwain. Born 1st April 1960, hard to believe he would be 56 today."
The tweet included links to a Google search of McElwain's paramilitary past.
Mrs Foster has previously named McElwain as the man she believed tried to shoot dead her father.
Speaking to the Belfast Telegraph, the DUP leader said he should be remembered for his past as "an evil and sectarian killer".
"He is not someone to be remembered in any warm way," she added.
The First Minister also accused Lynch of seeking to rewrite the past.
"I have used the scars of the past to motivate me to build a better Northern Ireland for my children," she said.
"But so long as people like Lynch try to rewrite the past, I will expose them at every turn.
"Glorifying McElwain sends an utterly mixed message to dissident republican terrorists."
The furore comes just days after Lynch caused anger among unionists after an anti-British rant during an Easter commemoration in a border village.
The Sinn Fein MLA said that the British Empire "was built on oppression, discrimination, torture and death".
McElwain was a member of the IRA's south Fermanagh brigade, and was previously linked to at least 10 murders.
These included the killings of off-duty UDR man Aubrey Abercrombie near Florencecourt, and Ernest Johnston, an off-duty RUC Reserve Constable, near Roslea, both in 1980.
On April 26, 1986, McElwain and Lynch had been preparing a huge landmine to ambush an Army patrol on the Lisnaskea to Roslea road. However, the SAS was waiting for them and opened fire on the pair, killing McElwain.
Lynch was seriously wounded and spent four months in hospital before being jailed for 25 years for possession of explosives and a rifle.
He was released in 1998 under the terms of the Good Friday Agreement and elected a Sinn Fein MLA for Fermanagh-South Tyrone in 2011.
In a BBC interview earlier this year Mrs Foster said that she believed McElwain attempted to murder her father John Kelly in 1979. The part-time policeman was shot in the head by the IRA at the family farm near Roslea, but survived.
Mrs Foster also spoke of the difficulties caused by Deputy First Minister Martin McGuinness's graveside oration at McElwain's funeral.
Mr McGuinness said McElwain was a "freedom fighter murdered by a British terrorist".
Referring to yesterday's tweet, Mrs Foster said it was wrong for Lynch to glorify McElwain.
She added: "McElwain was a notorious gunman. He was behind the murder and attempted murder of many Protestants along the Fermanagh border.
"I am led to believe that he was the man who came to murder my father.
"He is not someone to be remembered in any warm way. He was, as the judge said, a dangerous killer.
"McElwain was shot as he was planning to murder soldiers. Had he not escaped from the Maze Prison, he wouldn't have come into contact with the SAS.
"Whilst at his funeral he was labelled as a freedom fighter, he is remembered locally as an evil and sectarian killer.
"Sean Lynch was also preparing to ambush those soldiers. Lynch says that McElwain would have been 56 years old now, but makes no mention of Corporal Aubrey Abercrombie or Constable Ernest Johnston, who were murdered by McElwain."
Lynch's post also drew condemnation from a Fermanagh-based victims' campaigner.
Kenny Donaldson, from Innocent Victims United, said: "Sean Lynch, along with other 'comrades', are well aware that there is an election round the corner and in recent times he and others have upped their militant republican triumphalism.
"Because of the actions of Seamus McElwain, Sean Lynch and others, very many men and women never reached the age of 56 - in many cases they didn't even reach 25.
"Let's be absolutely clear: Seamus McElwain was a terrorist, he was a serial killer who roamed the south Fermanagh area along with Mr Lynch and others in search of their next victim."
It is the second time in a week that Lynch has caused anger over his views on the past.
On Monday during a Sinn Fein Easter commemoration in Pettigo on the Donegal-Fermanagh border he angered unionists with anti-British comments.
"The British Empire was built on oppression, discrimination, torture and death," he said. "Ireland, which endured centuries of occupation, was no different."
Citing the Easter Rising as a reason why he joined the IRA, Lynch went on to say the Provos had the same legitimacy as the men of 1916.