A son who killed his dad by repeatedly kicking him in the head was found guilty of murder on February 4.
Neil Badrock, 28, admitted manslaughter over his "ferocious, brutal and totally unforgiving" street attack on Neil Farrington, 51.
Witnesses described him "volleying" his father and screaming "I will f***ing kill you" in an attack lasting a full five minutes, Liverpool Echo reports.
It only ceased when police officers arrived at the scene and discovered Badrock still kicking his dad in the head, while shouting: "What do you think about that?"
Badrock accepted headbutting Mr Farrington to the ground, then striking and punching him, because he was "angry".
He claimed his father grabbed him by the throat, he "lost his head", and had never intended to kill or seriously harm his victim.
But a jury unanimously found him guilty of murder after six hours and 20 minutes of deliberation, following a four-day trial.
Badrock, of Kenbury Close, Kirkby, covered his mouth with his hand when the verdict was returned, while members of his family sobbed in the public gallery at Liverpool Crown Court.
He then slumped forward and bowed his head as Judge David Aubrey, QC, said: "There can be but one sentence and that is a sentence of life imprisonment."
The trial heard Badrock set upon his dad on Monday, May 17 last year, following a 10-hour "pub crawl" on the first day after lockdown ended.
Mr Farrington suffered injuries including a broken skull and brain injury, and, after spending five weeks in a coma, died in hospital on June 21.
Prosecutors said the victim had gone to The Mainbrace pub in Kirkby to try and calm his son down, after Badrock sent him texts about a man he had argued with at the pub, saying: "I will bite his f***ing windpipe out if I have to."
At one point the "very drunk" son ordered two pints of Strongbow, two Jager bombs, two Southern Comfort with lemonades and a sambuca, all at the same time.
The trial heard Badrock was asked to leave the pub after telling his dad to "f*** off", shortly after 11pm, before Mr Farrington caught up with him on Kirkby Row, close to its junction with Whitefield Drive.
There, the court heard Mr Farrington told his son "I'm f***ing sick of it, I've put up with it for 20 years", before pushing him and going to walk away.
A woman looking out a bedroom window said she saw Badrock turn his father around, then headbutt him to the ground, at which point she rang police.
Rebecca Alger, who burst into tears when asked to relive the harrowing 999 call, described Badrock "bashing" Mr Farrington's head on the pavement.
She said she could hear the noise of the younger man lifting the older man's head up and "banging it down onto the pavement", next to her front wall, before he starting kicking and stamping on him.
Ms Alger said at least twice Badrock started to walk away before returning to continue his attack, and that she thought it was her sister who described him as "volleying" the victim in the head.
Under questioning by Benjamin Myers, QC, defending, Ms Alger accepted Mr Farrington had first pushed Badrock away, but she said "not violently" and she thought this was a push to the chest, not a grabbing of the neck.
Guy Gozem, QC, prosecuting, said the attack was captured on grainy footage from a distant CCTV camera.
He said while Badrock may have gone down to the ground at the start of the incident, he immediately got back up, but after his father went down, "literally, he never gets up again".
Mr Gozem said: "Plainly what Neil Badrock did to his father has nothing to do with self-defence. What he did was in one sense tragic - a son killing his father. But it was, you may conclude, ferocious, brutal, and totally unforgiving, going on as it did for such an extended period."
When giving evidence, Badrock - who had no previous convictions - insisted: "I didn't want it to get to the level it got to."
The gym maintenance worker said his dad had earlier advised him to go home over text, but he didn't want to because "I was enjoying myself".
He said after he was thrown out of the pub, he realised he'd had "a ridiculous amount to drink" and just wanted to go home and sleep it off.
But he said his dad - who appeared "p****d" off - grabbed him by the throat and pinned him against a wall, which left him struggling to breathe.
The jury was shown photos taken after his arrest that showed marks on his neck, which he said were caused when "my dad had me by the throat".
Badrock said he headbutted Mr Farrington, then had an experience similar to a "blackout", telling the jury: "I just didn't realise what I was doing."
He had no explanation for punching and kicking his dad, saying: "I sit there every night before I go to sleep and I can't understand why it led to what it led to."
Asked how he felt, he said: "I feel sick… I have now lost a dad and it is devastating. It is devastating what I done. I can't believe I have done that to my own dad."
Under cross-examination by Mr Gozem, he said "After the headbutt, when he went to the floor, I just remember kicking him and punching him because I was raging at the time and I didn't know he was unconscious from the headbutt… I just, like a switch had gone off in my head, I had lost control."
Judge Aubrey said Badrock will be sentenced next Wednesday and remanded him in custody.
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