A large stone was discovered beside the grave of 86-year-old Mr Jack Maxfield, which is unmarked and in a private burial ground, and police believe it may have been used to smash a hole in the coffin to remove his head.
Mr Maxfield died two months ago of natural causes and was buried in the woodland site at Ulley, Rotherham, south Yorkshire. His head was cut off when the grave was desecrated last weekend and was found dumped 22 miles away in Oxspring, near Barnsley.
Acting Detective Superintendent Derek Deakin, leading the inquiry, said it was not the first time the grave had been disturbed.
He did not believe the attacks were directed at the Maxfield family, adding: "We are still not ruling out some form of ritual black magic as a possible motive."
Meanwhile, Mr Maxfield's son Philip said yesterday: "It is like something out of a horror novel."
He revealed that his 83-year-old mother was not aware of the full details of the attack, only that the grave had been disturbed.
Mrs Maxfield, who is partially sighted, suffers from a heart condition and has just been discharged from hospital after a six-month stay.
Philip Maxfield said his family could think of no motive. "We are shaken and horrified by the whole thing. We are trying to protect our mother's feelings as much as we can because we fear for her health if she finds out all the gruesome facts," he said.
The private burial ground, which has no headstones, was opened in October last year by two Lancashire funeral directors. There were a number of protests at the time and police have not dismissed the possibility that the desecration may be directed at the owners.
Mr Maxfield's remains have been removed for further forensic tests.Reuse content