Houseowner Danny Vanzandt, 66, was reported dead after the blaze in Sequoyah County, Oklahoma late last month.
Sheriff Ron Lockhart says neighbours entered Vanzandt’s house when they saw smoke and assumed some trash had caught fire. But when they got inside they saw that Mr Vanzandt himself was on fire.
Sheriff Lockhart said the dead man’s remains were found in the kitchen. There was no other damage to the house, and no apparent source of fire.
“This is a case that I’ve never seen before,” Sheriff Lockhart told a local television station.
“There was no damage to the furniture or anything around the fire, so it was a low heat fire,” he told the station.
No cause has been determined and Sheriff Lockhart says spontaneous combustion has not been ruled out.
“I think there’s only about 200 cases worldwide, and I’m not saying this happened. I’m just saying that we haven’t ruled it out,” the Sheriff told reporters.
He said the victim’s may have burned for 10 hours: “The body is burned, incinerated, like I’ve never seen before and it’s some kind of chemical reaction or something the way I can see it.”
The victim was an alcoholic and an avid smoker, factors that may have contributed to the body blaze.