I used to watch Unsolved Mysterious with my mommy when I was around 7 years old. It used to scare the crap out of me, especially the ghost stories.
Anyways, I found the following link below:
http://unsolvedmysteries.wikia.com/wiki/Dennis_Walker
Walker left Medford in April 1986 and vanished. Sixteen months later, on July 5, 1987, a man by the name of "Charlie Lee" was found dead in the bathroom of a Las Vegas hotel room. Authorities found a pill bottle on the counter with the name "Dennis Walker." Dental records confirmed that the dead man was Walker. A cause of death could not be determined; it is still unknown if his death was an accident, suicide, or homicide. Authorities would like to determine how Walker died; they would also like to find the rest of his collection.
I'm pretty sure a lot of cards from his collection are already sitting inside PSA holders and showing up for sale online regularly.