Gerry Hutch has been found not guilty of murdering a man at a Dublin hotel in 2016.
The 50-year-old stood trial accused of the murder of David Byrne who was shot six times at a crowded boxing weigh-in event at the Regency Hotel.
It was one of the first deadly attacks of the Hutch-Kinahan gangland feud in Ireland.
After a 52-day trial at Ireland’s non-jury Special Criminal Court, during which he did not give evidence, Hutch was found not guilty.
Separately, two men were found guilty of facilitating Byrne’s murder.
Paul Murphy, 62, and Jason Bonney, 52, were both charged with providing a motor vehicle to a criminal organisation.
During proceedings, former Sinn Fein councillor Jonathan Dowdall gave evidence as a prosecution witness.
Dowdall, who was to stand trial for murder, is serving a four-year prison sentence after he pleaded guilty to facilitating the murder of Mr Byrne.
Hutch’s defence team dismissed Dowdall’s evidence as unreliable and flawed.
Evidence presented to the court included a taped conversation between Hutch and Dowdall as they travelled to Northern Ireland, and a Garda interview conducted with Dowdall.
Ms Justice Tara Burns said that video recordings of Gardai interviewing Dowdall, conducted after the Regency murder, “make for very uncomfortable viewing”.
She said that the manner in which he told the lies to gardai “is extremely concerning for this court”.
“A significant question hangs over Jonathan Dowdall’s character,” she said and that because of his “patterns of lying, the court must approach his truthfulness with scepticism and extreme care”.