Detectives believe an ex-soldier turned bomb mule was beaten to death over a local dispute.
Larry Keane, 56, was found lying in a huge pool of blood on a walkway near a housing estate in Athy, Co Kildare, at about midnight last night.
The one time Irish soldier had served time in jail for trying to smuggle an explosive twice the size of the Omagh bomb into the UK in 1998.
But despite his links to dissident republicans, gardaí said his killing had none of the hallmarks of a paramilitary assassination.
Instead, they are focusing on rows the father-of-six had with others in the small town in recent months.
"He was living on his reputation," said one source.
"He used to be considered a heavy, but he wasn't in good health and didn't have the physique to back it up anymore."
Keane was found semi-conscious after suffering a severe blow to the back of his head.
Detectives believe he may have been kicked to death or a struck with a blunt instrument.
"This looks like a local job," said a source.
Keane, who lived near the scene of his murder and was well known around the town where he was regularly seen walking with a stick, was taken to Naas Hospital where he died in the early hours of this morning.
The alarm was raised when local officers were called shortly before midnight last night with a report of a man lying in the walkway between St John's Lane and Greenhills.
He was thought to be returning to his home in Canal Close when he was set upon.
It is understood the discovery was made by a young man who was walking his girlfriend home. Both were said to be shaken by the find.
Keane, who had children to a number of partners and was living with his son, was a soldier between 1974 and 1980.
During his trial for a major explosives offence in 1998, he said he was recruited while in Portlaoise Prison for assault and agreed to move the bomb "for a few bob".
He was jailed for 15 years after gardaí stopped him in a BMW car packed with explosives and queued for the ferry in Dun Laoghaire two days before the Aintree Grand National.
The 980lb bomb was twice the size of the device planted in Omagh a few months later.
Locals said he was in very ill health in recent years after a serious car accident and had mobility problems.
A number of neighbours described Keane as frail.
"I can honestly say that a 10-year-old could have knocked him down," one man who declined to be named said.
However, the dead man was handed a six-month suspended sentence in November for assault and came to the attention of gardai for a number of minor offences in recent years.
Gardaí sealed off the area where Keane was discovered for a forensic technical examination and have appealed for witnesses to come forward.
A dark-coloured jacket remained lying on the lane as children played beside the police cordon in the summer sun.
State pathologist Dr Michael Curtis is carrying out a post-mortem examination which will determine exactly what injuries the man suffered.
Forensic experts were also carrying out a search of scrubland next to the murder scene as Garda officers made door-to-door inquiries in the adjoining housing estate.
One neighbour said Keane used the lane every day on his way into town where he was regularly spotted sitting on the bridge.
"He was a familiar face in town," said another local. "I always found him very pleasant.
"Over the last number of years he was very unstable, and his speech was affected.
"To be honest, I can't imagine he would have the strength to be involved in anything."
Another said: "Larry was a decent old skin. There was no real bother with him. Some people liked him, some people didn't, but to beat a man that age is unbelievable."
Gardaí who were called to the scene last night tried to revive Keane using CPR before paramedics arrived and rushed him to hospital.
He was pronounced dead at around 5am.