Genealogy art

1988 Santee woman’s murder solved through genetic genealogy testing

Diane Lynn Dahn
Diane Lynn Dahn. Courtesy of San Diego County Sheriff’s Department

A genetic genealogy investigation has identified the killer of a Santee woman found dead in her apartment in 1988, the San Diego County Sheriff’s Department announced Wednesday.

The stabbing death of Diane Lynn Dahn, 29, is the fifth local homicide solved by genetic genealogy, sheriff’s officials said. The process matches DNA collected from crime scenes with samples submitted to public databases, often by people seeking to identify relatives.

Advances in DNA technology led to the eventual identification of a suspect, Warren Robertson, who lived in the same Graves Avenue apartment complex as the victim. Robertson died in a house fire in Indiana in 1999, officials said.

Although a DNA profile of the suspect has been compiled from fingernail scrapings and a hair found on the victim, no leads have been generated as to the identity of the suspect until recently. In 2020, a genetic genealogy investigation was undertaken, comparing the suspect’s profile to genetic profiles submitted on commercial databases, leading investigators to Robertson’s direct descendants.

According to Jeffrey Vandersip, the sheriff’s homicide crime analyst, the profile was matched against those of users who agreed and consented to law enforcement performing a genealogy analysis.

The technology gained widespread notoriety through its use to identify the Golden State Killer, who was convicted and sentenced to life in prison for a series of murders and rapes in the 1970s and 80s. in San Diego County, technology led to the identification of murder victim Laurie Diane Potter and the arrest last year of her then-husband Jack Dennis Potter, who investigators say killed her in 2003.

Sheriff’s Homicide Detective Brian Patterson said he had “no doubt in my mind” that the Dahn case would not have been solved without the genetic genealogy testing.

At a news conference announcing the resolution of the case, Dahn’s sister, Victoria Dahn-Minter, said she was “very grateful” to investigators for continuing to pursue the case after she became cold.

“I thought I was going to go to my grave myself not knowing (what had happened),” she said.

City News Service contributed to this article.