it didn't even wake him up. the obvious conclusion 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 which he planned to use to attempt to raise these latent prints? >> the process is called super glue fuming. heated super blue produces fumes that adhere to a fingerprint, and the add he's is greater than fingerprint powder. >> you want to preserve anything on that rock as far as latent prints and fingerprints and want to make sure there's no way that, by using a brush, it's going to come off. >> unfortunately, the surface of the rock was too jagged.