However, that was where he was taken yesterday after the Dubliner was found guilty of killing his stepson, Dean Fitzpatrick, the older brother of missing teenager Amy Fitzpatrick.
Prison officers led him from court to be remanded in custody for sentencing on May 30.
The 45-year-old had been cleared of murdering Mr Fitzpatrick, a father of one on May 26, 2013, with whom he did not get along. He had pleaded not guilty. The jury, eschewing a murder verdict, returned a majority verdict of manslaughter.
The 23-year-old victim received a stab wound to the abdomen outside the apartment his mother, Audrey Fitzpatrick, shared with Mahon at Burnell Square, Northern Cross, Dublin 17.
The State argued Mahon had been drunk, angry, and agitated when he thrust a knife into his stepson with deadly intent.
Mahon claimed his death was an accident or possible suicide and Mr Fitzpatrick had “walked into the knife” while they were arguing.
The trial heard Mahon had been in a relationship with Audrey Fitzpatrick for 12 years by the time her son died. The couple had moved to Spain’s Costa del Sol with her children, Dean and Amy, in 2004. Mr Mahon worked as an estate agent. He told gardaí they were millionaires, with eight or nine houses and bars, but they had spent it all looking for Amy.
The teenager went missing without trace on New Year’s Day, 2008, as she walked home from a friend’s house along an unlit dirt track. Despite extensive searches, she has never been found.
Dean Fitzpatrick was 17 when his sister vanished. He moved home to Dublin soon after turning 18 and lived with his father, Christopher Fitzpatrick. He met his partner, Sarah O’Rourke, in 2010. They had a son together and lived in Lusk in the north of the county. Mahon and Audrey Fitzpatrick returned to Ireland more recently and the court heard they have married since Mr Fitzpatrick was killed.
The trial heard the deceased had psychological issues, had begun misusing drugs at the age of 11, and had self-harmed. Ms O’Rourke gave evidence he used to take “relaxers”.
She also testified she had asked him to move out just days before he died, because he was selling tablets. She saw him with a black eye the morning of the fatal row; he had said he owed someone money. A quarter of an hour before the fatal row, she sent him a text saying she was with someone else “to hurt him”.
His father gave evidence that Dean was troubled during the last week of his life.
“There was stuff going on with his girlfriend,” he said, adding, as far as he was aware, the deceased could not see his child. “Also, his sister was missing,” he said .
The accused told gardaí he and Dead Fitzpatrick had “an up-and-down” relationship. However, they had joined a gym together and both attended separately the day before the row. The deceased saw his stepfather’s bicycle parked outside and took the water bottle off it to annoy him. It worked.
Staff in the gym Told Mahon there was nothing they could do unless he reported it to gardaí but he said he would not do that over a water bottle. He decided instead to contact his stepson.
He spent much of the next day drinking and phoning Dean Fitzpatrick. Records showed several unanswered calls. Ms O’Rourke said Mahon threatened to stab her in the neck if she did not get her partner to call him back.
Mahon eventually convinced Dean to come to his apartment.
It is not known if the deceased, while he was in the apartment, noticed the photographs of his sister and Mahon’s late mother strewn on the floor. Other family photographs and certs Amy had given the couple were found behind the building.
Mahon said Dean pulled a knife on him in the apartment and he had wrestled it from him and put it into his pocket. He said the deceased had left but he followed him out and took the knife out to show it to him. He said Mr Fitzpatrick then walked into it.
Two of Mahon’s friends were in the flat at the time: Karl O’Toole and John McCormack.
Mr O’Toole did not see any knife until Mahon returned after the stabbing. He said he did not really know what had happened but Mahon had asked him to get him out of there. Mr O’Toole drove him around the back roads of Dublin for a number of hours before eventually bringing him to Mahon’s father’s house.
Mr McCormack left the flat with the deceased but did not give evidence and the judge told the jury not to speculate about that.
The trial heard Dean had run downstairs, but collapsed outside and bled to death internally. The knife had damaged a number of organs, as well as the aorta.
The prosecution pointed to a number of threats Mahon had made to stab his stepson.
The defence said these were not serious and perhaps part of a particular vernacular. His barrister, Seán Guerin, referred to the pathologist’s view that it was possible Mr Fitzpatrick had walked onto the knife.
He also said suicide had to be considered, pointing to what had been going on in Mr Fitzpatrick’s life and the unknown effects that medications found in his system might have had.
Mr Guerin also suggested the possibility that Dean had seen the knife but had failed to appreciate the danger. He reminded the jury he had mentioned to medical personnel he felt like Superman when he drank.
Ms Justice Margaret Heneghan told the jury three possible verdicts would be open to them: Guilty, not guilty of murder but guilty of manslaughter, or not guilty.
Following eight hours and 16 minutes of deliberation over three days, the jury returned yesterday afternoon with a majority verdict of 10 to two.
Mr Guerin applied for bail for his client, pointing out he had lived in Spain after the incident, but had returned home to be charged. The State objected and the judge remanded him in custody for sentencing.