Gardaí are still trying to establish how a 29-year-old man who died yesterday in Dublin sustained his head injuries.
The man has still not been formally identified, gardaí said last night. However, he is believed to be either Lithuanian or Russian.
The emergency services and gardaí were summoned to assist him when he called to an apartment complex in the Islandbridge area of the city looking for help late on Sunday night.
He was brought to St James's Hospital where he died later.
The three occupants of the apartment are understood to have only known the man by sight. They were interviewed by gardaí in Kilmainham yesterday.
The scene around the Bridgewater Quay apartment complex was preserved for technical examination.
Gardaí said last evening it was still not clear how the man received his injuries but it appeared he had been the victim of a serious assault.
"We have an idea of who he is, but he still has not been formally identified," a Garda spokeswoman said.
The man's body was removed to the city morgue for a postmortem examination which was being carried out last night by State Pathologist Prof Marie Cassidy.
Gardaí have appealed for witnesses. Supt Eddie Quirke said detectives were still trying to trace the victim's last movements.
"We are appealing for help from the public in relation to the movements of this person, particularly people who live in the Bridgewater Quay apartment complex and on Conyngham Road which is in Dublin 8," he said.
"We are also appealing to the Lithuanian community or indeed the Russian community that could help us to identify this person and to give us an account of his last movements.
"Our initial information was that he was a Lithuanian national. We are not sure now if that is correct so we are appealing to members of the Lithuanian community and indeed the Russian community in Dublin who may know the identify of this person," Supt Quirke said.
Anyone with information should contact Kilmainham Garda station on 01-6669750.
If the victim is Lithuanian he will be the fifth man from his community to have died violently in the Republic this year.