LA Forensics: Mysterious Confession

Sign: SID

SID Criminalist Annie Eyevazoff was tasked with the job of trying to find enough DNA markers on the 30-year-old slides to compare with those of the detectives' suspect, Andrew Lancaster.

SID Criminalist Annie Eyevazoff

The samples were older than Eyevazoff.

Examining the DNA

The first two sets of slides she looked at were a bust. The vaginal samples from the Masters and Fellows cases had dried up and left no detectable DNA.

Although the rape kits and swabs from the 1970s are nearly identical to those used today, the procedures for storing the samples have changed.

"Back in the 70s, most of the kits were stored at regular room temperature," Eyevazoff says, "whereas today we usually store them in the freezer to slow down or prevent the degradation of DNA caused by the bacteria that may be present with the sample."

There was one last set of slides — those from the Lois Petrie case.

Examining the DNA

If those slides were in the same condition as the ones from the other two cases, the investigation into Andrew Lancaster was going to hit yet another, this time likely final, dead end.

Eyevazoff pulled out one of the Petrie slides.

"I examined it under a microscope and was able to detect sperm on the slide," the SID criminalist says. "I was pleasantly surprised that we were able to obtain a DNA profile from a sample that was so old."

Examining the DNA

After 30 years, detectives had the DNA profile of Lois Petrie's killer. Now all they had to do was compare it to the DNA profile of their suspect. It sounded simple enough, but as always, there was a catch, one that threatened to once again let a killer go free.