Soham killer Ian Huntley's cause of death has been revealed.
Huntley, 52, died in hospital after being struck multiple times over the head with a metal bar, an inquest has heard.
He was left with "significant head injuries" after being attacked inside the prison workshop in HMP Frankland, County Durham, in late February.
The killer was reportedly found by prison guards in a pool of blood.
He died days later on 7 March at Royal Victoria Infirmary in Newcastle.
His cause of death was determined as "blunt head injury".
The former school caretaker was serving a life sentence after being convicted of killing 10-year-olds Holly Wells and Jessica Chapman in Soham, Cambridgeshire, in August 2002.
The inquest, held in Crook, County Durham, on Tuesday, lasted less than five minutes.
Coroner's officer Bradley King said: "I understand the circumstances to be that Mr Huntley was struck over the head multiple times by another prisoner with an object described as a metal bar.
"The assault left Mr Huntley with significant head injuries."
Huntley's body was formally identified on the day he died.
Anthony Russell, 43, who has been charged with murdering Huntley, is due to have a pre-trial hearing at Newcastle Crown Court on 24 April.
Huntley, a former school caretaker, killed best friends Holly and Jessica after they left a family barbecue to buy sweets in Soham, Cambridgeshire, in August 2002. He dumped their bodies in a ditch 10 miles away.
They were not found for 13 days, despite a search involving hundreds of police.
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At the time, Huntley lived with Maxine Carr, who was a teaching assistant at Holly and Jessica's primary school.
He denied murdering the girls but was convicted after a trial at the Old Bailey in 2003. He was jailed for life with a recommended minimum term of 40 years.
Carr gave Huntley a false alibi and was jailed for 21 months for perverting the course of justice.
She is now living under a new identity.
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