A 24-year-old man was being quizzed last night over the murder of father-of-two Vincent Parsons.
Gardai believe at least two people were involved in the brutal assault in Tallaght which left him with fatal injuries.
Detectives have been following a definite line of inquiry into the murder, and believe the 34-year-old welder was targeted following an argument at a pub near where he was found.
As part of their investigation, gardai yesterday arrested a 24-year-old man in connection with the attack.
He was taken to Tallaght Garda Station under Section 4 of the Criminal Justice Act, and remained in custody last night after being interviewed on suspicion of murder.
Mr Parsons was found with serious head injuries in the Killinarden estate in Tallaght at around 11pm on Saturday.
He was unconscious and covered in blood when he was found by a passing member of the public, who alerted emergency services.
Senior investigators said this week that Mr Parsons' injuries were so severe that gardai rushed him to hospital themselves instead of waiting for an ambulance.
Following a post-mortem examination, gardai upgraded their investigation to a murder probe.
Supt Ian Lackey, of Tallaght Garda Station, said Mr Parsons, from Clondalkin, suffered horrific injuries after being attacked near the pub.
"The initial findings indicate he met with a very violent death. A lot of people have come forward to date," Supt Lackey said of the witnesses gardai have interviewed.
"There is no indication of weapons being used. We believe at least two people were involved."
More than 50 gardai are now involved in the investigation, Supt Lackey said.
Investigators have been making good progress with their inquiries, which include examining CCTV footage and taking witness statements.
Two suspects have already been identified as part of the investigation, including the man currently in garda custody.
A number of witnesses have already come forward, but gardai are particularly keen to speak to motorists, taxi drivers or anyone else who was in the vicinity of the Killinarden Inn pub between 10 and 11pm on Saturday.
Gardai in Tallaght are also continuing to appeal for anyone with information or who may have witnessed the assault to contact them.
Officers have also carried out searches of a park close to where Mr Parsons was found.
The attack was one of two violent incidents in Tallaght over the weekend.
On Sunday afternoon, a 33-year-old man was found with serious head injuries in the Cloonmore Green area.
He was taken to Tallaght University Hospital with a suspected bleed to the brain and a punctured lung.