A former boxer who repeatedly punched and stamped on the head of man, leaving him physically and mentally disabled, has been jailed for eight years.
Reece Green, 24, went looking for a man he believed was responsible for an alleged crime in the early hours of Friday 4 August.
Taking the law into his own hands, drunken Green banged on the doors of flats above Gallagher's bar just outside Carlisle city centre.
When entirely innocent Thomas McMillan told Green forcefully to go away, his door was broken down and he was ferociously attacked.
Green then dragged 56-year-old Mr McMillan - bleeding and barely conscious - into the street and learned he was not responsible for any crime.
Yet he then delivered a hard punch, stamped on his head and left him unconscious on the ground before placing him in the recovery position and fleeing.
Green, of Fernlea Way, Carlisle, later told a friend: "I think I've killed him."
The city's crown court heard Mr McMillan suffered multiple fractures, had footprints on his face and shoulder, and was left with a "profoundly life-changing" brain injury.
He spent three weeks in intensive care, and will rely on others to provide physical and mental care for the rest of his life.
Green - involved in boxing and taikwondo as a younger man - admitted causing Mr McMillan grievous bodily harm with intent, and criminal damage.
Described as "ashamed" and "disgusted" of what he had done, he was jailed by Judge Peter Davies.
"You embarked upon a sustained, savage and ferocious attack on an innocent man in his own home," Judge Davies told him.