The inquest into the death of murderer Michael Chudley was told that he suffered cardiac failure.
Chudley, 63, died in his cell at Winchester Prison on April 8.
He was found unresponsive in his cell shortly before 5.50am. CPR was attempted but he was pronounced dead at 6.36am.
Chudley was serving a life sentence for the murder of Devizes solicitor Jim Ward who he shot at point blank range in Mr Ward’s office, MGW Law, St John’s Street, on July 2, 2012. Mr Ward, 58, of Bratton, died almost three weeks later.
The inquest into Chudley’s death was opened on Tuesday at Chandlers Ford, Hampshire, by senior coroner Grahame Short.
He was told the cause of death was a fractured cervical spine and congestive cardiac failure due to ischaemic heart disease.
The inquest was adjourned for investigations to be carried out and further tests.