Crime Library: Criminal Minds and Methods

LA Forensics: The Sandwich Shop Murders

A Promising Case

The cash register was taken for analysis. Its last registered transaction had occurred that morning at 1:32: a turkey and bacon sandwich, a seafood sandwich, and two tuna salads. According to the tape, the items had not been paid for. Thus, it seemed very possible that the shooter had handled the dropped sandwich, since it had been turkey and bacon, but it was not easy to lift fingerprints from plastic bags, so latent print technicians concentrated on other items first. When they got few prints from the cash register, chips bags collected from the counter, or coins from the register's drawer, they turned to the plastic bag. Feeling pressure to find something that would nail a suspect, if identified, they worked cautiously.

Scott Hurwitz, Forensic Expert
Scott Hurwitz, Forensic Expert

Scott Hurwitz, a latent print analyst, refrained from applying the typical method of black fingerprint powder to make prints on the bag visible, for fear of smudging them. He turned instead to a different type of processing cyanoacrylate fuming, also known as Superglue fuming, which is done inside a special hood. Discovered in Japan in 1978, it is a chemical method that reacts with acids and proteins in the sweat that leaves the print impression.

"It's heated up," Hurwitz explained, "and the fumes will collect onto the surface where the fingerprint is." The glue hardens and the print is thus more easily preserved than with a powder. With this method, SID managed to get a good impression of a left thumbprint and a left index finger on the bottom of the bag. However, after putting the impressions through the AFIS database, where they were compared against millions of others in digital storage, they found that no one with a prior criminal record had committed this crime.

Nevertheless, the detectives believed they had a promising case. "We had prints," said Officer Moseley, "and we had ballistics. It was a good crime scene. It had a lot of evidence that could be processed."

They would soon have more.

We're Following
Slender Man stabbing, Waukesha, Wisconsin
Gilberto Valle 'Cannibal Cop'