Ian Huntley died from a blunt head injury after being attacked by another prisoner at HMP Frankland, an inquest has heard.
The 52-year-old, who was serving a life sentence for the murders of 10-year-old schoolgirls Holly Wells and Jessica Chapman in Soham in 2002, was struck multiple times with a metal bar during the incident on 26 February.
He sustained significant head injuries and died nine days later, on 7 March, at the Royal Victoria Infirmary in Newcastle.
Opening the inquest in Crook, County Durham, senior coroner Jeremy Chipperfield said Huntley’s death was caused by blunt head injury, following a post-mortem examination by forensic pathologist Dr Jennifer Bolton.
The coroner confirmed the inquest would be suspended pending the outcome of criminal proceedings.
Anthony Russell, 43, has been charged with Huntley’s murder and is due to appear at Newcastle Crown Court on 24 April.
Huntley had been jailed for life with a minimum term of 40 years after being convicted of murdering Holly Wells and Jessica Chapman, who disappeared in August 2002 after leaving a family barbecue in Soham, Cambridgeshire.
The girls bodies were found in a ditch around two weeks later following a major national search.