The two suspects were arrested on Saturday evening following the discovery of a body of a 26-year-old man at a house on Spa St, Portarlington at around 5pm.
The scene was preserved for a technical examination and a preliminary autopsy was carried out by assistant State pathologist Dr Margot Bolster yesterday morning.
Gardaí said the results would determine the direction of the investigation. It is expected to be upgraded to a murder inquiry.
It is understood the dead man was a Latvian who lived in the house along with one of the men detained by gardaí. His remains were yesterday transferred to the Midland Regional Hospital in Tullamore for a full post mortem.
Detectives understand the man had been drinking with others for several hours on Saturday before a row broke out, in which he received a number of stab injuries.
The two men questioned by gardaí are in their early 30s and mid-40s and are believed to be Lithuanians.
Anyone who passed near the stabbing scene is asked to contact Portlaoise Garda Station on 057 8674100
Local Fianna Fáil councillor Raymond Cribbin said local people were shocked over the young man’s death.
“I’d see them. I often go by the house. They seemed to be nice fellas and it’s a tragedy that it took place,” he said.