A 26-year-old man was being quizzed last night over the murder of a father-of-two who was beaten to death on the way home from a night out last month.
He was the second man to be arrested in relation to the death of Clondalkin man Vincent Parsons.
Mr Parsons (34) was found by passers-by in Killinarden Estate, Tallaght, with serious head injuries on August 24.
He died two days later in Tallaght Hospital.
The 26-year-old man was arrested yesterday on suspicion of murder and was being detained at Tallaght Garda Station.
A 24-year-old man was released without charge after he was arrested last month on suspicion of the murder. A file is being prepared for the Director of Public Prosecution.
It is understood Mr Parsons sustained head injuries during an assault in and around the Killinarden House pub, where he had been socialising.
The Herald previously revealed that gardai were investigating if at least two men were involved in the murder.
Speaking to reporters outside Tallaght Garda Station last month, Chief Supt Ian Lackey said welder Mr Parsons suffered horrific injuries after being attacked.
His injuries were so severe that gardai took him to hospital themselves instead of waiting for an ambulance.
"The initial findings indicate he met with a very violent death," Mr Lackey said.
"A lot of people have come forward to date.
More than 50 gardai are now involved in the investigation, he added.
Mr Parsons was unconscious and covered in blood when a member of the public found him at 11pm and alerted the emergency services.
Gardai arrived and rushed him to Tallaght Hospital in their patrol car, but he died two days later.
Last week, Mr Parsons was laid to rest after his funeral mass at the Church of the Transfiguration in Bawnogue.
His son, Gerard, brought his father's welding helmet to the altar as a symbol of his life, as well as a back scratcher.
His daughter, Jade, carried a photo of the family.
At the end of the mass a relative, also named Gerard, spoke on behalf of the family, telling mourners that everyone learned from Mr Parsons and looked up to him.
"He was one of the nicest and most honest men you could ever meet," he said.
"He was the same man to us all, and life was too short for Vincent. Life can be cruel at times, and this is one of those times."
Fr Patrick Coughlan said everyone he had spoken to about Mr Parsons' death have been "utterly shocked".
"We can only imagine the chaos that it has caused his wife and young family, his mother and his brother and sisters," he said.
"What shocks is the suddenness of his going. He is here and then he is suddenly gone.
"Also, the tragic, horrible circumstances of his death and the devastation left behind for those who love him."
After funeral mass the remains of Mr Parsons, who was from Melrose Lawns, were brought to Newlands Cross cemetery for burial.
Gardai have appealed for witnesses to come forward.
Anyone with information is being urged to contact Tallaght Garda Station on 01-6666000 or the Garda Confidential Line on 1800 666 111.