An 86-year-old woman found murdered in her bungalow had been repeatedly stabbed and then set on fire, police have said.
The body of widow Una Crown, who lived alone and had no children, was discovered on the floor in her bungalow in Magazine Lane, Wisbech, Cambridgeshire, shortly after 11am on Sunday.
A post-mortem examination has since established that she had been "brutally" assaulted. On Thursday, Cambridgeshire Police confirmed that Mrs Crown's body was set alight after she was killed.
Mrs Crown was last seen alive on Friday and spoke to a friend by telephone at about 5pm on Saturday. A post-mortem examination revealed she died as a result of stab wounds to her neck and chest. Mrs Crown's clothing was set alight but the fire did not spread to the rest of the house.
Detective Chief Inspector Jon Hutchinson said: "This was a horrific murder of a defenceless elderly woman in her own home. She was stabbed several times, then set on fire in an apparent attempt by her killer to hide her injuries and destroy evidence.
"The fire damage meant it was difficult to initially establish the cause of Mrs Crown's death. However, the stab wounds were revealed during the post-mortem on Tuesday evening."
He repeated a call for witnesses to come forward. He said: "Did a friend or loved one come home on Saturday night or Sunday afternoon smelling of smoke? I would urge you to do the right thing and call police to ensure the killer is caught and brought to justice."
Forensic examinations were continuing at Mrs Crown's bungalow and officers are carrying out house-to-house inquiries.
Mr Hutchinson said the case was not being linked to any other crimes in the area but said one possibility was that Mrs Crown had been killed after a suspect broke into the house. The detective said there was no evidence of a sexual assault and the property had not been ransacked.
Anyone with any information should call the major crime unit on 101 or Crimestoppers, anonymously, on 0800 555111.