LA Forensics: The Keystone Diamond

Two things were done this time around that hadn't been done during the initial investigation.

The first was a comparison of Scott's fingerprints before and after the murder. Then, the altered prints were run through a computer system that was not available in 1983. It filled in the missing part of the print and was an exact match to the prints on the flashlight and to Scott's first set of fingerprints.

Secondly, Hernandez wanted a better time frame of when the murder happened, so he asked the criminalists to put new batteries in the flashlight, turn it on, and watch to see how long they lasted. 

The batteries lasted about 3-1/2 hours, meaning that the crime couldn't have happened earlier than 5 a.m. Either roommate Dennis really did hear a car backfire at 2:30 a.m. or he was mistaken about the time.

District Attorney Sydney Trapp

Hernandez drove from the coffee shop of Scott's alibi to William's house. Scott could've easily been there shortly after the murder but no one working there remembered anything.

It was time to get the district attorney involved.

"Ray had a long history of putting together difficult cases," said Los Angeles County Deputy District Attorney Sidney Trapp. But more evidence was needed before filing the case.  

"I think it would be really taking a chance with a jury if you only thing you had was a thumbprint, which could've been put anytime on the flashlight," Trapp said. "I would not want to go to a jury with just a thumbprint on a flashlight."

Through witnesses, Hernandez had located an ex-girlfriend of Scott's, in Phoenix. Trapp thought she could be the key — he'd obtained valuable evidence from girlfriends in past cases.

"I told my boss that I would file the case if he put two tickets on my desk to Phoenix for the next morning," Trapp said.

Sure enough, the next day Hernandez and Trapp knocked on the door of Sarah Hull in Phoenix.

A pretty woman answered.

"Well, I figured you'd get to me sometime," she said.