Pearse McAuley
It is understood the former Provisional IRA man may have lay dead in his native town of Strabane for a number of days.
Locals believe the 59-year-old died from natural causes.
McAuley walked free from prison in 2022 after serving his time for a brutal knife attack on his ex-wife.
He stabbed Pauline Tully, now a Sinn Féin TD, 13 times in 2014.
McAuley had previously served a sentence for killing Detective Garda Jerry McCabe in 1996, for which he was released from prison in 2009.
Sinn Fein stood by McAuley and three other IRA killers after the 1996 killing of Det Garda McCabe during an armed robbery.
McAuley was jailed for 14 years but released in 2009 after serving 10.
The party claimed he should have been released under the Good Friday Agreement and had fought for his early release despite Irish government opposition.
McAuley met Ms Tully when she visited him in jail. They married in 2003 as he was serving his sentence. They have two children.
He shot his way out of Brixton Prison in London in 1991 and fled to the Republic.
After his release for the McCabe killing, the Crown Prosecution Service said it would not seek his extradition for the escape.
The ex-Provo was later disowned by republicans following the attack on his wife.
