LA Forensics: Mysterious Confession

Testing the DNA

Unlike TV crime dramas like CSI: Crime Scene Investigation, real-life forensic work takes time. In the case of Lancaster's DNA comparison, the detectives had to wait a month for the results.

Testing the DNA

"A coffee cup was brought into the laboratory for swabbing for possible DNA that may have been left behind by the suspect," SID Criminalist Annie Eyevazoff says. "When the DNA profile from the swab of the cup was compared to the DNA profile obtained from the Petrie case, it was determined that there was a match between those two evidence samples."

Comparing the DNA

Bengtson and Flores had their match.

To say they were happy would be an understatement.

"I was sitting in a parking lot when I got the phone call," Flores recalls. "The criminalist had me on speaker phone. Everybody in the office was listening to me and they tell me that it matched. I screamed, I screamed in the parking lot by myself, in my car. It was total joy."

On Sept. 5, 2003, Bengtson and Flores arrested Andrew Lancaster for the murder of Lois Petrie. When the cold case detectives tried to interview him at the station, Lancaster pretended to cooperate while at the same time denying once again that he'd had anything to do with the three San Pedro murders.

"Then we told him about the DNA," Flores says, "and at that point he said, 'I think I need to talk to my attorney' and that was the end of the interview."