He was named as Seán Kennedy, a single man aged 54, who lived with his elderly mother.
Mr Kennedy’s body was discovered about 300 yards from his home at Ardnataggle, Ballina, at around 10am yesterday.
He was last seen alive leaving a local pub the previous night.
Chief Supt Liam Quinn said: “We want a post mortem to establish the full facts of what happened. We are investigating the circumstances and want a full examination of the body.”
He said there were no apparent marks on Mr Kennedy’s body.
The late Mr Kennedy was a nephew of Paudie Skehan who was murdered in his home by a Limerick criminal in 1998.
Meanwhile, gardaí in west Limerick are still trying to trace a teenager who failed to return home after a night out in Abbeyfeale.
Ricky Loughnane, 18, was last seen at around 3.20am on Sunday morning.
Gardaí believe he may have been given a lift part of the way to his home in Dromtrasna.
A helicopter yesterday joined locals and gardaí as they combed the countryside near where he was last seen.