Convicted Garda killer Pearse McAuley has been found dead at his home in Strabane, aged 59.
A PSNI spokeswoman said on Tuesday: “Police are examining the circumstances surrounding the death of a man at a property in Abercorn Square in Strabane on Monday, 18 March.
“At present, the death is not believed to be suspicious.”
Mr McAuley was part of the IRA gang that shot dead Detective Garda Jerry McCabe in Limerick in 1996, and was sentenced in 1999 to 14 years in jail.
Mr McAuley and his IRA gang shot Det Gda McCabe and his partner Det Gda Ben O’Sullivan during a raid on the post office in Adare, Co Limerick, on June 7th, 1996.
The killing occurred four months after the breakdown of the first IRA ceasefire.
While McAuley was serving his sentence, Sinn Fein made an unsuccessful attempt to have him and others jailed for the garda killing to be released under the terms of the Good Friday Agreement.
The move was resisted by the Government.
McAuley was convicted along with Limerick men Jeremiah Sheehy, Michael O’Neill and Kevin Walsh.
In 2014, Mr McCauley stabbed his then wife, Sinn Féin TD Pauline Tully. He was given a 12-year sentence for the attack with the final four years suspended.
Mr McCauley was released from prison in 2022 for the attack.
The pair had married while McAuley was serving his 14-year sentence for the garda killing.
They met when Ms Tully, who was elected as a Sinn Féin councillor in 1999, visited McAuley at Castlerea Prison in Co Roscommon.
They became engaged in 2000.
He was temporarily released in 2003 to marry Ms Tully, a teacher at the time, in her home village of Kilnaleck, Co Cavan.
Mr McAuley pulled off a prison escape in England in 1991 while awaiting trial on terrorism charges.
On July 7th, 1991, he had escaped from Brixton Prison along with cellmate Nessan Quinlivan. He was being held on charges of conspiring to cause explosions and in connection with a plan to murder a British brewery company chairman.
The two men had been arrested in October 1990, at Stonehenge in connection with the murder plot.