Former INLA man Dessie O'Hare, who was known as 'The Border Fox', has pleaded guilty at the non-jury Special Criminal Court to assault and false imprisonment in Dublin.
O'Hare (62), of Slate Rock Road, Newtownhamilton, Co Armagh, admitted to assaulting John Roche, causing him harm, at The Towers, Garter Lane, Saggart, Co Dublin, on June 9, 2015.
He also pleaded guilty to falsely imprisoning Martin Byrne at Rathcoole and Saggart on the same date.
Sean Guerin SC, defending, told the three-judge court a trial would not be required and Mr O'Hare could be arraigned on two of the counts.
Dressed in a shirt and tie, O'Hare stood up and faced the court.
When the registrar read the two counts on the indictment to O'Hare and asked him how he was pleading, he replied "guilty" to both.
Shane Costelloe SC, prosecuting, said Mr Guerin had informed him there were some outstanding matters on his side of the house.
Following this, Mr Guerin said his client had had some engagement with "professionals" and the defence wanted to have up-to-date professional assistance for the sentence hearing.
Mr Justice Tony Hunt, presiding, sitting with Judge Patricia Ryan and Judge Ann Ryan, remanded the defendant on continuing bail with the same terms and conditions until April 3, when he will be sentenced.
O'Hare was previously linked to at least 26 IRA murders by gardaí and the RUC in Armagh - even before he had reached his 20th birthday.
But O'Hare is most infamous for the kidnap and imprisonment of dentist Dr John O'Grady in 1987.
He has served 16 years of a 40-year sentence for the kidnap, carried out along with the INLA.
The terrorists went on the run with Dr O'Grady for three weeks, during which time O'Hare removed the tips of two of Dr O'Grady's fingers with a chisel.
Their intended target was Dr Austin Darragh whose firm, which tested pharmaceuticals, was reputed to have made him one of the richest men in Ireland. The gang had his old address and were not aware he had passed on his former home in Brennanstown Road, Foxrock, Co Dublin, to his daughter Marise, her husband Dr O'Grady and their three children, when he moved to another house in Ballsbridge.
Dr O'Grady was reunited with his family on November 5, 1987, and able to resume his career at his Ballsbridge surgery. He died in September 2016 at the age of 67.
Eight months before the kidnapping, O'Hare and associates kidnapped and tortured Monaghan man Tony McCluskey, who they suspected of siding with another republican faction against them.
O'Hare used bolt cutters to slice off parts of McCluskey's anatomy before finally shooting him dead.