A woman has been missing for ten weeks. Her kidnappers murder her, torch the body until it is unrecognizable, then dump it in the woods, confident that the charred, black chunks of tissue that remain are too scorched for police to identify. No body, no crime.
Such was the situation faced by police recently in Mexico. They had found the charred husk of body and nearby, the high school ring of a woman who had been missing for ten weeks. Unfortunately, the fire had thoroughly consumed any usable tissue from which to extract a DNA sample.