Loyalist leader Mark Haddock has been cleared of the murder of paramilitary rival Tommy English 12 years ago.
The 40-year-old UDA chief was shot in his house in Newtownabbey, Co Antrim, in front of his wife and three children in October 2000, during a bloody feud between the Ulster Volunteer Force (UVF) and the UDA.
The 21-week trial at Belfast Crown Court was one of the longest in Northern Ireland's legal history and is set to be one of the most expensive.
Only one of the 13 defendants in the "supergrass" trial was convicted.
Neil Pollock was convicted of two minor charges, while the other 12 have been acquitted of all charges.
Today's judgment was handed down amid tight security.
The 13 defendants, ranging in age from 32 to 46, faced dozens of offences, including murder, kidnapping and UVF membership.
Nine of the men, including Mr Haddock, were accused of murdering Mr English in what the prosecution said was a "tit-for-tat" killing during the loyalist feud.
Evidence against the defendants centred on testimony from former UVF members, brothers Robert and David Stewart.
They claimed they were in the flat in New Mossley, north Belfast, when the plan was hatched to kill a "hair bear", a nickname for a UDA member.
In return for giving evidence, they were given substantially reduced sentences for their part in Mr English's murder.
Defence lawyers described their evidence as being "totally and completely unworthy of belief".
The judge said today that they were not reliable witnesses.
Under cross-examination, the brothers denied they had received "the deal of the century" and said they had only wanted to do the "right thing".
The trial before Mr Justice Gillen was the first "supergrass" trial in Northern Ireland since the 1980s.
The non-jury trial broke new legal ground with the judge allowing journalists to tweet from court during the trial for the first time.
In another unique move, the judge ordered that written skeleton arguments by defence lawyers and particular rulings made during the trial be made available for the public to view.
