SEQUOYAH COUNTY, OK (CNN/KFSM) -- Oklahoma authorities investigating a mysterious death have come up with a rare theory. They are looking into whether or not a 65-year-old man died from spontaneously bursting into flames.

Family members found 65-year-old Danny Vanzandt dead Monday inside his home on Bawkin Road outside Muldrow. Sheriff Ron Lockhart says, "The body was burned and it was incinerated."

Lockhart told 5News in a telephone interview he believes the death could be a rare case of spontaneous human combustion. Lockhart says, "I think there's only about 200 cases worldwide and I'm not saying that this has happened I'm just saying that we haven't ruled it out."

Lockhart says the fire didn't damage the house and there were no signs of struggle. He says, "There was no damage to the furniture or anything around the fire, so it was a low heat fire."

Family says they noticed the back window of the man's pickup truck was busted out. Investigators sent the body to the medical examiner's office in Tulsa. Lockhart says, "If you read about spontaneous human combustion that's what we have here."

The sheriff says Vanzandt was an alcoholic and avid smoker. When asked if it was possible Vanzandt accidentally killed himself some other way like dropping a cigarette on himself, Lockhart says, "And a cigarette burn will not do that."

The autopsy report is pending.