The jury accepted George Gonzaga Bento's position that he was acting in self-defence after being attacked by a gang when he and a colleague tried to retrieve a stolen bike.
He said he had pulled out a utility knife that he carried for cutting fruit and stabbed three people, including 16-year-old Josh.
They rejected the State's contention that Mr Bento had decided to take the law into his own hands, had exaggerated the threat posed by his attackers and knew at the time that the force he used was not necessary to repel the attack.
Mr Bento has been in custody for about 18 months having been refused bail by the High Court, but following the verdicts, Judge Mr Justice Paul Burns told him he is free to go.
A prison officer told the court that Mr Bento would be released from the court building. Mr Bento smiled and hugged family and friends when the verdicts were announced.
Members of Josh Dunne's family, including his mother, quickly left the court.
The jury of seven women and five men took a little over eight hours to reach unanimous verdicts on all counts following a six-week trial.
The prosecution alleged that Mr Bento produced a knife during a "stand-off or confrontation" with a man on a moped who had stolen another delivery cyclist's bike. Josh Dunne and other youths arrived at the scene and got involved in the confrontation.
Mr Bento told gardai in his interviews that he had used a knife to defend himself from the man on the moped and the gang of youths.
He said it was only his intention to intimidate them when he took out the knife and make them go away. He said he stabbed the first and second males who punched and attacked him as he was scared and wanted to protect himself.
Josh, an unarmed teenager who was unknown to gardai, did not initially attack Mr Bento or Mr Quieroz but just held the moped while the attack continued.
When he saw Mr Bento stab his friend, Josh reacted by punching Mr Bento repeatedly before being stabbed. CCTV captured the moment that Josh separated from the group and stumbled to the ground.
While being interviewed by detectives at Store Street Garda Station in Dublin's inner city, George Bento asked them if they had seen ‘City of God’, Fernando Meirelles' 2002 film about life in the notorious slums of Rio.
The 36-year-old told them that life was difficult growing up in Brazil. Although he said he never got involved ‘in anything unlawful’, he had lost a lot of friends to the scourge of crime and drugs. However, he had a strong family around him who kept him safe and made sure he got a good education.
"It's a hard situation but it's happy. I worked a lot and I always try to improve my life," he said.
George came to Ireland in February 2019 to better himself. "I watch movies and read. I realised that first world countries had good education and opportunities...so I needed to try [sic]," he said.
Life in Ireland was good at the beginning. "I can work, study and improve myself," George said, and he found employment as a food delivery cyclist.
It was in Dublin though where he also encountered violence and intimidation. He said gangs of youths would deliberately attack him with stones and eggs. George told his trial that his reaction was "always avoid and always try to go away".
"For them it was fun, for us we were working and trying to improve life,” he said.
In broken English, George told the jury that he never came to Ireland “to make problems” but rather to work. “My intention is to do something good and never something bad," he added.
Assistant State Pathologist Dr Heidi Okkers said Josh suffered two stab wounds to the chest. The cause of death was a wound to the middle of the chest that pierced the muscle between the ribs and entered the chest cavity, piercing the lung close to the heart. It had also penetrated the aorta, the largest blood vessel in the body.
The accused took the stand during the trial and said that he and his friend Guillherme Quieroz had followed a bike thief through Dublin but when they tried to retrieve the stolen bike, they were set on by a gang of men and youths.
Mr Bento said he feared for his life and that of his friend and that he used the knife to defend them from serious injury or death. He told the jury that he believed the level of force he used was necessary to keep him and Mr Quieroz alive. "I believe I saved two lives, mine and Guilherme lives [sic]," he said.
Mr Quieroz also gave evidence, telling the jury that he believed Mr Bento saved him on two occasions, first when he was forced up against a wall and repeatedly punched and a second time when he was dragged to the road while being struck.
Mr Bento's defence counsel, Padraig Dwyer SC, told the jury that his client is an innocent, hard-working man who used reasonable force to defend himself and his friend Mr Quieroz from a "punishment beating" inflicted on them because they tried to retrieve a stolen bicycle.
Prosecution counsel, Sean Guerin SC, said that when Mr Bento produced the knife a second time and used it to stab one of the alleged victims, the teenagers were backing away and neither he nor his friend were under attack.
He said that Josh Dunne, who had no involvement in the assault up to then, reacted to seeing his friend being stabbed by using reasonable force in punching Mr Bento to push him away.
Counsel described Josh's actions as "commendable" but said Mr Bento reacted to Josh's reasonable response with lethal force that he knew was not necessary to protect himself or his friend.
Mr Justice Burns had charged the jury that, in relation to the murder charge, if it was reasonably possible that the accused acted in defence of himself or another and used no more force than was necessary, he should be found not guilty.
Where a person used more force than was reasonably necessary but no more force than he honestly believed was necessary, the verdict would be not guilty of murder but guilty of manslaughter. If the prosecution had proved beyond reasonable doubt that the accused knew the amount of force used was not reasonably necessary then he would have been guilty of murder.
Mr Bento (36), a Brazilian national with an address in East Wall in Dublin 3, had denied murdering 16-year-old Josh Dunne at East Wall Road, East Wall on January 26, 2021.
The jury also acquitted Mr Bento of producing a utility knife in a manner likely to intimidate another in the course of a dispute or fight. He was further acquitted of assault causing harm to two other young men on the same occasion.
The trial heard that two other men got involved in the altercation just as Josh separated himself from the group. Mr Quieroz was beaten by these two men and Bento responded by stabbing one of them.
This 29-year-old man, who cannot be named for legal reasons, denied to the jury that he carried out a “vicious attack” on Mr Quieroz on the night and had only stopped after he was stabbed in the back. The jury heard the man has several previous criminal convictions, including those for bike theft, the possession of drugs and criminal damage.
Following the verdicts, Mr Justice Paul Burns thanked the jury and exempted them from further service for seven years.
During the trial, the jury saw CCTV footage showing a man on a moped picking up a delivery cyclist's bike and driving off with it.
Mr Bento and Mr Quieroz followed him and retrieved the bike but the moped man did not go away and when a group of teenagers arrived, including Josh, the moped man assaulted Mr Quieroz, sparking the fatal row.
The prosecution described the moped man as a bike thief and a thug who should be condemned for launching a violent and unlawful attack on Mr Bento and Mr Quieroz. He was, they said, the "instigator" of the trouble that led to Josh Dunne's death.
Mr Bento's defence counsel said the blame for Josh's death lay with the moped man and not with Mr Bento. At the beginning of their deliberations, the jury questioned why the moped man was not called to give evidence.