A teenager armed with a cricket bat crept up on a man and murdered him with a single blow to the head, a court heard.
The 16-year-old boy – who cannot be named for legal reasons – is accused of killing Derek Whyteside as the 42-year-old searched for two stolen bikes on an estate in Telford on the afternoon of 18 June.
Stafford Crown Court has heard how Mr Whyteside – who lived with his partner and her four children – was attacked by three people, one of whom was the youngster who struck him with the bat.
Prosecutor Kevin Hegarty told the jury of six men and six women how the alleged murderer "crept up behind" the victim as he looked for the bikes.
"He was looking for two stolen bicycles and also he was looking for those responsible for stealing them," he said.
"Whilst he was there, he was struck across the back of the head with a bat. The impact fractured his skull and the fracture extended into his right eye socket.
"Before he could take another step, he then collapsed on the ground."
Mr Whyteside – who was carrying a knuckle-duster at the time of the attack – suffered a further fracture when his head hit the floor, and he died two days later.
The teenager, who denies a single charge of murder, was said to have inflicted a "full swing" upon Mr Whyteside and intended to do "really serious harm" to him.
He claimed in a police interview that he had acted in self-defence, and later told officers he had been defending his mother, but Mr Hegarty said his argument was not credible.
He told the jury: "This is not a case of self-defence. It was not necessary to swing the bat with such force so as to break his skull and cause him to collapse.
"He wasn't under any attack from Derek Whyteside – he wasn't even looking at him. What was going through this young man's mind when he struck the blow was to cause as much damage as he possibly could."
After hitting the ground, Mr Whyteside was struck by two other men, William Owens and Gareth Owens, 41 and 39, who both avoided a trial after admitting charges of affray.
Mr Whyteside's partner, Michelle Beddall, later tried to call him several times but each went unanswered.
Earlier in the day, Ms Beddall – who works as a carer – had gone to the 16-year-old's home to speak to his mother after watching a neighbour's CCTV footage of the bikes being stolen.
She told the court how the boy laughed after she spoke to him about the bikes, while his mother claimed the youth in the footage was not her son.
"I was a little bit intimidated so I then walked back towards my car," she said.
"They were calling me names."
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She added in the witness box that she later phoned Mr Whyteside and could hear him saying "just leave the bikes", before the further calls to him went unanswered.
The trial continues.