Gardai say they are now treating the death of a man in Churchill as suspicious.
Gardai are looking for witnesses who may have seen Mr Callaghan alive.
The body of 50 year old Kieran Callaghan was found at his home in the Roshin area of Churchill on Sunday afternoon.
At first it was thought he died of natural causes but the scene was preserved for an investigation.
State Pathologist Marie Cassidy carried out a post mortem on the dead man’s body today.
As a result of her findings, Gardai say they are now treating Mr Callaghan’s death as suspicious.
They have appealed for anyone who may have seen Mr Callaghan in the Letterkenny or Churchill area on Friday to come forward.
The father-of-four was a part-time farmer who also worked at Glenveagh National Park.
It is understood Mr Callaghan may have suffered a head injury before he was found dead at his home.
Further tests are to be carried out on the body.
A short time ago, a Garda spokesman said: “Gardai are appealing to the public in tracing the whereabouts and last movements of Kieran Callaghan from Roshin, Milford, Co. Donegal between Thursday the 4/07/13 and Sunday the 7/07/13 at 1.30pm. He was last seen in the Churchill area of Letterkenny at approximately 6pm on the 5/07/13. Kieran is described as being 5’10” in height with grey hair and of thin build.
“Anyone with information or who can assist with the investigation is asked to contact Milford Garda Station on 074-9153060, The Garda Confidential Telephone Line 1800 666 111 or any Garda Station.”
