An attack victim died more than a year after a "vicious" street assault by a serving soldier, a court heard.
Joseph Leech suffered a badly fractured skull and brain injuries after Karl Pascoe hit him repeatedly with a plank of wood in December 2013.
Newcastle Crown Court heard the 32-year-old victim survived as a result of expert medical intervention but developed epilepsy and was "never the same again".
On April 2 last year Mr Leech ,who was prone to suffering fits in his sleep, went to bed at his parents' home for an afternoon nap and "never woke up".
His body was found by his mother.
Pascoe, who was convicted of assault in the aftermath of the attack, is now accused of murder.
The 31-year-old, of Blackfell, Washington, denies the charge and is being tried by a jury.
Prosecutor Nicholas Lumley QC told the court: "It was this defendant who assaulted him, this defendant caused him to be in the vulnerable position, whatever the delay between the events, it was this defendant who caused his death.
"The defendant must bear criminal responsibility for Joseph Leech's death."
Mr Lumley told the court the death was a "tragedy" for all involved, including Pascoe, who was a "promising soldier" with a good record of service.
The court heard the violence happened in the street near Mr Leech's home at Woodland Terrace in Washington.
Mr Leech, who had been drinking at home and arguing with a friend on the telephone, was out in the street after midnight, carrying a piece of wood.
The court heard Pascoe, who was walking along the street with his girlfriend after a night out, was a stranger to Mr Leech and there was no history or "bad blood" between them.
Mr Lumley said the violence may have been a result of Pascoe wanting to "take the law into his own hands" or even "trying to impress" his then girlfriend.
Witnesses told police it was Pascoe who ended up with the piece of wood, which he used to inflict multiple blows.
It is claimed Pascoe walked away mid attack then came back to inflict more violence, while Mr Leech was defenceless on the ground.
The court heard Mr Leech's dad John witnessed some of the violence inflicted on his son from the widow of his home.
Mr Lumley said: "He realised he had to get dressed and go out and run down to help his son but it was too late.
"By the time he got out into the road his on was lying out cold, blood was pouring from his head.
"The defendant hadn't even waited to see if the victim of his assault was alright."
The court heard one witness had heard Pascoe telling Mr Leech "you won't **** with me anymore" during the violence.
The court heard a previous jury, before Mr Leech's death, found Pascoe not guilty of attempted murder in relation to the attack.
Mr Lumley said a conviction for attempted murder requires proof of an intention to kill whereas a conviction for murder requires only an intention to cause really serious harm.
Pascoe denies murder.
The trial continues.