The family of a man who was killed after he tried to intervene in a "domestic" dispute between another man and his partner have said they cannot forget or forgive his killer.
Mr Mullally, 56, had been out celebrating his retirement with family and friends when a cyclist told him he had seen a man acting aggressively towards a woman on Harold's Cross Road.
He and a friend - Shane Cunningham - went to intervene and he was punched by Dargan before falling to the ground and hitting his head.
A post-mortem examination showed his jaw and face had been broken in three places and this could have been caused by a single punch. He died the following day.
Dargan, a martial arts instructor, pleaded not guilty but was convicted by a jury of manslaughter.
He was also convicted of assaulting a passing cyclist, who said he saw him "throw fairly powerful" punches, while shouting "bang, bang."
In a victim impact statement to the court Mr Mullally's widow Joan Shields said she had to tell their ten-year-old daughter that her Daddy "went to help a lady who seemed to be in trouble but was punched and knocked to the ground and wasn't coming home."
She also said that Dargan had "left him there and walked away to his car."
Dargan was subsequently arrested by gardaí
Ms Shields said her husband would miss his daughter growing into the "beautiful, caring, gentle person" she is and she would "never be able to forgive him [Dargan] for that."
Referring to Dargan, Mr Mullally's niece said that "one person had ripped several lives apart in a few minutes with his bare hands."
Because of this man's actions he has left a family with a dark hole in their lives which can never be filled," Courtney Mullally said.
"If he had kept his hands to himself that night we would have an extra person sitting at our table at Christmas."
The court heard that even though Dargan had pleaded not guilty he accepted the jury's verdict of manslaughter and had written a letter of apology to Patrick Mullally's family.
His defence counsel said alcohol was a factor, and that he had drank cocktails and driven drunk that night.
Dargan was also convicted of assaulting Mr Cunningham.
Ms Justice Pauline Codd remanded Dargan in custody to be sentenced later this week.