Murdered Dublin man Tyrone McKenna was savagely stabbed twice at the top of the stairs of his home before he staggered downstairs and collapsed.
A woman in her 40s, who was known to Mr McKenna, has been arrested and is being questioned by gardai at Blackrock garda station.
The victim (42) was discovered by his distraught father Thomas on the stairs of their family home at around 5pm.
A large kitchen knife has been recovered from the scene.
A post-mortem examination on the body of Mr McKenna was carried out yesterday by the Deputy State Pathologist and forensic examinations continued at the scene.
The victim's grieving father told the Herald that he can still see his son's body as he found him at their home in the quiet Marley Court estate in Rathfarnham on Thursday evening.
"My son didn't deserve this," Mr McKenna said last night. "I want to find out what happened and start putting it behind me."
The dead man's mother, Theresa, lives in Surrey, and Mr McKenna said: "She was in such a state of shock when we rang her, she had to put the phone down.
"I discovered it, I was out yesterday morning and I came back to the house.
"He was there at the foot of the stairs. I touched him and I knew straight away, and I rang 999."
Mr McKenna said that Tyrone was in the house with a woman who, when he asked what happened, said that she just heard a "thud".
"I don't know how long he was dead at this stage (when he was found)," Mr McKenna said.
"I didn't pick him up or anything like that. His mouth was wide open, he was dead. He was on the last few steps just kind of slumped backwards.
"It was as if he had slid down. There was blood on the wall, and there was blood on the landing."
Mr McKenna was at the scene yesterday morning with his daughter Revenna, who said that the tragedy had not hit them yet.
"It's a peculiar kind of feeling," Mr McKenna said.
His daughter added: "It doesn't seem real, it just hasn't hit us yet."
Mr McKenna said that his son had a history of mental health problems and he had urged him to get help.
"He should have been in hospital yesterday. I kept telling him, 'You're not well, just go to hospital'."
Revenna said her brother was a music-lover and was involved in pirate broadcasting when he was younger.
Tyrone, who was out of work, married in 2003 but has been separated from his wife for a number of years.
Locals said they were utterly stunned at the shocking turn of events.
"I knew him as a lovely young man. The family have been there longer than us, which is 25 years," one local man said.
Gardai are treating the death as a murder investigation and have appealed for any information.
The woman arrested can be detained without charge for a maximum of 24 hours, excluding rest periods.
The suspect's period of detention was extended by a senior officer yesterday afternoon. Gardai said they were following a definite line of inquiry.