Gardaí are investigating the circumstances surrounding the death of a man at a flat on Dublin's North Circular Road last night.
Gary O'Brien, 51, who was originally from Barry Avenue in Finglas was found with gunshot wounds to his head at around 8.30pm.
The scene remains sealed off for a forensic examination as gardaí seek to establish how he was shot.
There were some suspicions that his injuries may have been self-inflicted but gardaí have so far been unable to find the gun used in the shooting.
A post-mortem examination is being carried out, which may lead to the case being reclassified as a murder investigation.
No arrests have been made but three people who were in the building at the time are helping gardaí with their inquiries. One, a woman, was wearing bloodstained clothes.
There was also evidence of some drug-taking in the house and a second house, which is boarded-up and derelict, about 100m away has also been sealed-off
Gardaí are appealing for witnesses or anyone with information to contact them.