what information you may have. then a mysterious figure emerges. police release grainy surveillance video that shows someone running from the burning porsche. could this be the killer? but the most important break comes from an unlikely source -- a piece of pizza. >> it just so happens that the fire never really hit that slice of pizza. that is what broke this case. >> for dna experts like lawrence kobilinsky, it's a pot of gold. >> you have a lot of cheek cells that tend to slough off into your saliva. there's a lot of dna in saliva. every time you bite into something, you are leaving small