Police investigating the murder of a man whose head swelled to twice its normal size after he was attacked have criticised hospital staff for failing to report the assault.

Ambulance crews found Joseph Byrne in a flat at Herschel Crescent, Littlemore, Oxford, after a caustic liquid had been poured over his head, burning his face and neck.

The 61-year-old, of Oxford Road, Rose Hill, told paramedics he had been assaulted.

He was taken for treatment at the John Radcliffe Hospital and then to the specialist burns unit at Stoke Mandeville Hospital, Aylesbury.

He suffered a heart attack caused by swelling blocking his breathing and died three weeks later without regaining consciousness.

Police launched a murder inquiry after his death and made one arrest, but failed to secure enough evidence or any witnesses.

An inquest into his death on Thursday at Oxford Coroner's Court criticised the hospitals.

DS Kevin McGuire, who led an police appeal for information, told the inquest: "We could have carried out investigations, taken evidence from the address and carried out forensics."

But vital evidence from the flat at Herschel Crescent was missing after landlords carried out renovations, and no witnesses to an alleged assault in Green Park in Littlemore were found.

A 42-year-old woman, formerly of Herschel Crescent, was arrested on suspicion of murder but released without charge.

Mr Byrne was found on May 7 2002, but died on July 1, 2002 at Stoke Mandeville Hospital after suffering a heart attack and brain damage. Paramedic Barry Pritchard told the inquest he found Mr Byrne, a former carpenter originally from Ireland, in the flat.

He said his head as twice its normal size, his eyes were tightly shut, his skin stretched tight and he was suffering breathing problems.

Dr Michael Tyler, of Stoke Mandeville Hospital, told the inquest the burns were caused by a caustic alkaline liquid, probably a household cleaning product.

A relative of Mr Byrne, who asked not to be named, said: "A man was dying in hospital and nobody thought to inform the family or the police.

"Somebody did that to him. It was a murderous act."

Delivering a narrative verdict, assistant deputy coroner Dr Richard Whittington said: "They the hospitals must have realised they had a public duty to inform police.

"I will be writing to them to remind all staff of their obligations, because if the investigation had started earlier, it would have greatly assisted the police."

Anyone with information should call DS McGuire on 08458 505505 or Crimestoppers on 0800 555111.