Two Dubliners were being questioned at separate garda stations in the capital last night on suspicion of the murder of a 44-year-old man.
The body of tragic Alan Hall was discovered at his home in Bluebell Avenue in south Dublin on the morning of last May 18 - a post-mortem revealed he had suffered injuries to his head and neck in a brutal assault.
The alarm was raised by a neighbour who heard smoke and carbon monoxide detectors going off.
Dublin Fire Brigade brought the blaze, which was in the bedroom, under control.
When firefighters searched the house, they found Mr Hall dead in the bathroom with injuries to his head and neck.
There were some indications the back door of the house may have been open when the emergency services arrived.
Last night, a senior source told the Herald that gardai have not yet been able to establish if Mr Hall had died as a result of the assault he had suffered or from smoke inhalation caused by the fire.
"A post-mortem showed that there was smoke in his lungs so the big question has been trying to establish if the injuries he received in the violent assault were enough to have killed him or if the smoke killed him," the source said.
"The two suspects who were arrested are being questioned on suspicion of murder and they were known to Mr Hall and are suspected of being in the property on May 18," the source added.
Like Mr Hall, the suspects have been staying in "supported accommodation" in the Bluebell area of the capital but at a different address.
The duo, aged 33 and 29, who live together are known to gardai for minor offences linked to misuse of drugs and public order offences.
It is understood Mr Hall was also battling addiction issues but he "was in the process of turning his life around" at the time of his death, according to a source last night.
Gardai yesterday announced details of the planned arrests, which were carried out by Clondalkin officers.
"Both men were arrested in the Dublin area and are currently detained under Section 4 of the Criminal Justice Act, 1984 at Clondalkin and Lucan Garda Stations," a garda spokesman said.
Mr Hall is understood to have previously worked as a butcher and while he was known to gardai he was not a serious criminal and had not come to the attention of the force for some time.
He was described by neighbours as a "quiet but helpful" man. He lived on his own in the end-of-terrace cottage where the fire was reported at 11.20am on Monday, May 18.
Neighbours said last month that Mr Hall usually "kept himself to himself" but would sometimes have friends around.
"He was a lovely fella. He would do anything for you. He had been shopping for someone the day before this happened," one neighbour said.
"We used to have a few drinks on special occasions and he was a nice lad. It's very sad."
The neighbour said Mr Hall had been seen the day before the fire and did not have any visible injuries.