Meet a team who have made it their macabre mission to find out.

"A human limb burns a little like a tree branch," says John DeHaan, a fire investigator at Fire-Ex Forensics in Vallejo, California, who works with Pope. First, he says, the thin outer layers of skin fry and begin to peel off as the flames dance across their surface. Then, after around 5 minutes, the thicker dermal layer of skin shrinks and begins to split, allowing the underlying yellow fat to leak out.

"That's when the fire gets most interesting," says DeHaan. Body fat can make a good fuel source, but it needs material such as clothing or charred wood to act as a wick. Like that in a wax candle, a wick absorbs the fat and pulls it into the flame, where it is vaporized, so enabling it to burn.

Burns cause agonizing pain. People in fires are "lucky" if the smoke kills them before the flames reach them.

Being burned alive is indeed the most excruciating death of all.