A KILLER ELUDES POLICE FOR 31 YEARS - HOW DID ONE WOMAN FIND HIM IN JUST TWO HOURS?

"48 Hours" Investigates in "A Killer in the Family Tree"

Saturday, Nov. 20

When Chelsea Rustad uploaded her DNA to a public database hoping to find other branches of her family tree, she never expected that process would prompt a visit from police investigators. The police were at her Washington state home with devastating news - someone in her family may have committed a double murder. 48 HOURS and correspondent Erin Moriarty immerse viewers in the case of a killer who eluded police for 31 years, then was identified in just two hours by genetic genealogist CeCe Moore, in "A Killer In The Family Tree" to be broadcast Saturday, Nov. 20 (10:00 PM, ET/PT) and streamed on Paramount+.

The broadcast features interviews with Rustad, who unknowingly found herself in the middle of a murder investigation, and Moore, who was able to quickly identify Rustad's relative - using genetic genealogy in her first criminal case. It's a story that starts with the murders of Tanya Van Cuylenborg, 18, and her boyfriend, Jay Cook, 20, in 1987, and raises questions about the use of genetic databases by everyday people and how the new wave of investigators can bring life to cold cases.

"I had no inkling at all that ... that there were secret relatives I didn't know about or mysteries to uncover," Rustad says.

Then the police visited her.

"They let me know they are investigating a family member of mine for murder," Rustad says, "a double homicide from 1987. ... This was a person in my family tree."

For more than 30 years, investigators in Washington state had been trying to solve the murders of Cook and Van Cuylenborg. At the time, police were concerned a serial killer might have done it. The killer remained a mystery until DNA found on Van Cuylenborg's pants was uploaded to the same database where Rustad had loaded her DNA. Moore, known for her work on the PBS series "Finding Your Roots," was called in to help find the person who matched the unidentified DNA.

"It's the web of matches," Moore says. "It's putting those pieces together little by little."

"Genetic genealogy has exposed a lot of secrets that people had hoped would remain secret," Moriarty says to Moore.

"Yes," Moore says. "Oftentimes, it's someone's deepest, darkest secret."

How did Moore narrow down the suspect? And how did he elude investigators so long? 48 HOURS and Moriarty have the details.

48 HOURS: "A Killer in the Family Tree" is produced by Lisa Freed, Sarah Prior and Mary Ann Rotondi. Lauren Clark is the field producer. Sara Ely Hulse and Charlotte Fuller are the development producers. Shaheen Tokhi and Addison Briley are the associate producers. Michael McHugh is the producer-editor. Atticus Brady and Michael Baluzy are the editors. Peter Schweitzer is the senior producer. Nancy Kramer is the executive story editor. Judy Tygard is the executive producer.

48 HOURS is broadcast Saturdays at 10:00 PM, ET/PT, on CBS and streams on Paramount+. Follow 48 HOURS on Twitter, Facebook and Instagram. Listen to podcasts at CBSAudio. Stream 48 HOURS on Paramount+.