The martial arts expert who formerly trained with UFC champ Conor McGregor has begged the forgiveness of the family of a Dublin dad who died after he punched him.

Jonathan Dargan hit former Guinness worker Paddy Mullally (57) outside an apartment complex in Harold's Cross in the early hours of Saturday, March 5, when Mullally tried to intervene in a row.

Mr Mullally died the next day from the head injury he received when he fell backwards from the punch and hit his head on the ground.

He had earlier been to his retirement party and stopped off at his local, Peggy Kelly's in Harolds Cross, for a drink on his way home.

It was as he was leaving that he spotted Dargan and a woman fighting on the street.

"I'm so sorry. It was an accident. I'm devastated and heartbroken for that man and his family. All I can say is I'm crushed," said Dargan.

"If I could take back everything that happened that night I would, but all I can do is beg his family for their forgiveness. It was a genuine mistake."

Dargan had been drinking on a night out with his partner when somebody asked him about his mother, Mary, who was shot dead two years ago in Tallaght. His sister Karina was also injured in the attack.

A man is currently before the courts in connection with the shooting, but it is believed that Dargan was in a low mood after he was asked about his mother because it was Mother's Day the following day.

Heartbroken

Dargan works as a doorman at the popular Lillie's Bordello nightclub, off Grafton Street, and also teaches Taekwan-do to children, but he has no previous convictions and has not come to the attention of gardai before.

Sources close to Dargan have said he left Lillie's after being out with his partner and got into his car, which he had intended leaving in town for the night. They had earlier been to the Adele concert.

"His girlfriend had been pleading with him not to drive but he was too far gone to listen. It was 3.30am and Jonathan had been drinking since 8pm," the source said.

"He pulled over in Harold's Cross and she got out of the car. He went back to try and convince her to get back into the car and found her at a bus stop, and the argument started again."

It is understood that Dargan told gardai they were first approached by a man on a bicycle who asked what was going on and that Dargan had cursed at him.

Dargan then recalled that there were two or three people around him.

It is believed he told gardai that he hit one of them and had a row with a second man before another person tried to drag him away.

After he got out of this person's grip he thinks he hit Paddy, grabbed his girlfriend and got back into his car.

Sources say Dargan woke the next day with little recollection of what happened and went to work on Saturday night as normal.

But while he was there he heard of the reports of the assault in Harold's Cross.

Questioned

After work, he drove towards his home before pulling in to a filling station, where a garda told him they were making inquiries about silver cars that had been out the night before.

At that stage it is believed Dargan told gardai he believed he was the man they were looking for.

He was brought to Terenure Garda Station and questioned, and broke down when he was told of Paddy's death. He was later released without charge and a file will be sent to the Director of Public Prosecutions.

Paddy Mullally's funeral is due to take place tommorrow in the Church of St Pius X in Templeogue at 11.30am.

Herald