Geoffrey Bulman from Newcastle, represented by Sam Stein QC and Mark McDonald, cleared of murdering his dad in Heaton home
He always denied attacking his dad, claiming either his mother or someone else was responsible.
Now he has been cleared of murder by jurors at Newcastle Crown Court.
He was also found not guilty of assaulting his neighbour after he complained about noise.
Jurors were told Mr Bulman, who was in his early 70s, in remission from cancer and had had a tracheostomy, suffered multiple injuries to his face, head and body and died from a minimum of seven blows to the head.
Prosecutors claimed it was Bulman’s mistaken belief that something was going on between his partner and his father that sparked the alleged attack.
But Bulman, 46, who lived with his parents in a Tyneside flat on Stratford Grove West, Heaton, Newcastle, denied killing his dad between Christmas and New Year.
The court heard how Mr Bulman had been to Heaton Buffs club on December 28 and it is thought he may have arrived home some time around 7.30pm.
Bulman told police an argument blew up between his mum and dad and claimed his mum had attacked her husband in the main bedroom of the groundfloor flat, the court was told.
He also claimed his dad headbutted him but denied being violent back.
Bulman said in the dock that because his hands were riddled with arthritis he couldn’t even make a proper fist.
Bulman was also cleared of attacking upstairs neighbour Alan Dove the morning after his dad died.
Mr Dove, who had heard Bulman shouting the night before, told the court he was assaulted for asking him to keep the noise down but Bulman said he was acting in self defence.