through that window didn't even faze him. didn't even wake him up. >> the obvious conclusion that you have to draw from that is the guy was probably dead already. >> toxicology tests found no drugs or alcohol in leslie vaughn's system. so there was no evidence he was unconscious before he was killed. next, investigators sent the rock to the forensic lab for testing. >> i talked to a scientist and asked him if there was a process in which he plans to use to attempt to raise these latent prints. >> the process is called superglue fuming. heated superglue produces fumes that adhere to a fingerprint, and the adhesion is greater than fingerprint powder. >> you want to preserve anything that is on that rock, as far as latent prints, or fingerprints. you want to make sure there is no way, by using a brush, that it's going to come off. >> unfortunately, the surface of the rock was too jagged.