The body of 50 year old Kieran Callaghan was found at his home in Roshin near the town of Milford in County Donegal yesterday afternoon.
Gardai requested the services of the State Pathologist following the discovery. Based on the results of a post mortem examination on Mr Callaghan's remains they are now treating his death as suspicious.
However, they say that further test results will determine the direction of their investigation.
Appeal for information
Gardai in Milford are appealing for anyone who may have seen Kieran Callaghan over the weekend to contact them.
He was last seen in the Churchill area of Letterkenny at around 6 o'clock last Friday evening.
He is described as being 5 feet 10 inches tall with grey hair and of thin build.
Anyone with information or who can help gardai with their investigation is asked to contact Milford Garda Station