Daniel Gauld, 25, was heard shouting "die, die, die" as he repeatedly punched, kicked and struck Douglas Struthers, 62, with a metal pole during the attack at the victim's home in Bo'ness, Falkirk, on 14 September 2022.

Mr Struthers died three days later at the Royal Infirmary of Edinburgh.

At the city's high court this week, judge Lord Fairley described it as a "vicious, prolonged and savage assault".

The judge added: "You assaulted him with such severity that two of his teeth ended up in his lungs."

Lord Fairley noted that the victim was "not well known" to Gauld but had invited both the killer and witness Fiona Grigg into his home and provided them with hospitality.

The court heard that Gauld had been drinking cider and whisky before aggressively challenging Mr Struthers, who had mobility issues, to a "square go" (a fight).

Ms Grigg said Gauld repeatedly punched his victim in the face.

She said: "He used both hands. He wouldn't stop. It was like something out of Rocky [the boxing movie]."

Gauld kicked Mr Struthers in the face and repeatedly struck his victim on the head with a metal pole.

Witness attempted to intervene

Ms Grigg, who along with Mr Struthers' neighbours dialled 999, said she tried to intervene and shield the victim but was hit with the pole.

Gauld, who admitted lying to police during an interview, claimed he lashed out after being struck on the hand with the pole by Mr Struthers.

The killer told the court: "He hit me and I hit him back."

Lord Fairley stated that Mr Struthers had tramline bruising from being struck by the pole. He also suffered other injuries to his head and body.

The judge added: "The beating that you administered to Mr Struthers was so severe as to amount to murder."

Gauld had denied murder but was found guilty following a trial.

He was handed a life sentence with at least 20 years behind bars on Monday.

'You are someone who will say whatever suits your purposes'

The judge stated there were a number of aggravating factors in the case, including that the attack was unprovoked, a weapon was used, and Mr Struthers was a disabled man in his 60s.

He added: "This court must do what it can to signify society's revulsion at crimes of this kind committed against vulnerable people like Mr Struthers."

Lord Fairley accepted that Gauld had "expressed a degree of remorse", but added: "I treat that, however, with a substantial level of caution as it appears to me from the evidence I have heard that you are someone who will say whatever suits your purposes regardless of whether or not it is true."

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Following the court case, Detective Inspector Will Harley said: "This was a particularly horrific attack by Gauld on a man who was a stranger to him.

"The family of Mr Struthers and a large number of people in the local community were affected by the extent of violence used by Gauld and our thoughts are with them all."

The Police Scotland inspector thanked all those who assisted during the investigation.

He added: "Gauld will now face the consequences of his actions and this conviction shows that we will use all the tools we have to investigate and bring to justice those committing such brutal crimes."