Read about this years ago when I was still in school, I even had a book about mysterious happenings that had a few pages on it and included pictures of such victims, one was a guy that burnt whilst sitting on his toilet, so no nearby fires etc... all that was left of his person, was the lower part of one leg, complete with his slipper still on it???
Edit, here is the exact picture from my old book...
http://i53.tinypic.com/2wn93tj.jpg[MG][/QUOTE]
It's just the Wick Effect, very hot but localised fire. They've recreated it many times with pig carcasses and the like to understand it. Often just not enough fat or a wick on lower part of limbs.
[url]http://en.wikipedia.org/wiki/Wick_effect#1998_experiment[/url]
[edit]1998 experiment
A larger scale experiment conducted for the BBC television program Q.E.D. involved a pig's body being wrapped in a blanket and placed in a furnished room. The blanket was lit with the aid of a small amount of petrol. The body took some time to ignite and burned at a very high temperature with low flames. The heat collected at the top of the room and melted a television. However, the flames caused very little damage to the surroundings, and the body burned for a number of hours before it was extinguished and examined. On examination it was observed that the flesh and bones in the burnt portion had been destroyed.[4]
Although there's been more experiments than that, sure there was a study by one of the American forensic agencies.