Snohomish County cold case unit, genetic genealogy ID suspect in 1990 teen murder

In August of 1990, Michelle Koski had just turned 17. She was about to graduate high school and planned to go to college. On the evening of August 20, she got a ride to a teen hangout near Maltby where kids were known to drink and ride motorcycles, according to an episode of Dateline highlighting Koski’s case. It’s not clear who gave her the ride. Five days later her body was found in the woods near Highway 522 and Echo Lake Road by a woman walking her dog. She had been raped, beaten, and strangled.

More than 31 years later, Snohomish County Sheriff’s cold case unit says they have finally been able to identify a suspect in Koski’s murder.

“After years of investigating and new advancements in DNA technology and investigative genetic genealogy the suspect has been identified as Robert A. Brooks,” said Snohomish County Sheriff Adam Fortney at a press conference Thursday.

“After more than three decades of searching for answers following this terrible murder of their 17-year-old daughter, we can finally provide this family with some answers. No family deserves to go through what you all have been through, and I’m deeply sorry for your loss,” said Fortney.

“We worked on that case really hard, ruling out a lot of people with DNA evidence that we had looked at the crime scene. There was never a DNA match in the Combined DNA Index System (CODIS) and the case remained cold,” recalled cold case Detective Jim Scharf.

Brooks was in trouble a lot as a kid and he was released from prison August, 18 of 1990 at the age of 22. He was living with a relative just a few blocks from where Koski was living at the time, near the area she was last seen alive two days before the murder.

The cold case unit teamed up with Parabon Labs once again to solve this case with the help of genetic genealogy which uses unidentified DNA evidence from a crime scene and public ancestry databases to ID a person through family members.

In the Koski case, the DNA sample was a mix between the victim and the suspected killer. According to the sheriff’s office, the lab was able to “deconvolute the mixture and ensure that matches would lead to the perpetrator.”

Distant cousins had uploaded their DNA to a public ancestry database — but they were very distant relatives. That’s when genealogist Deb Stone from Oregon got involved, spending about 9 months building out a family tree that eventually led to two brothers – both dead – one of them Brooks.

Brooks was never on the investigators’ radar. He died in 2016.

Still, the identity of the killer brings long-awaited closure to Koski’s family and friends, several of whom were at this press conference Thursday, including Melissa Johnson.

“I have been praying for this day for a very long time. After almost 32 years, it’s finally come true,” said Johnson.

“Michelle and I met when we were just 10 years old. And I remember one day in the girls bathroom in the elementary school she asked me if I had a best friend. I said ‘no. Do you have one?’ And she’s like, ‘no,’ and she’s like, ‘you want to be my best friend?’ Of course. So that’s how we became best friends. I lost my best friend when we were 17 years old. I only knew her for seven years, but it was like a lifetime as a kid,” recalled Johnson.

“I miss her smile, and her laugh. I miss her being mad at me for calling her ‘Mitch’. I miss waiting four hours for her to wake up in the morning and then another three hours for her to get ready. I miss her always beating me at gin rummy. But I always kept the four of hearts in my hand just so she couldn’t have it because that was her favorite card. I miss her love of animals. I miss her protectiveness for the ones that she loved,” she continued, noting her best friend also could be very gentle and kind.

“I miss hanging out and playing Super Mario Brothers, I miss hanging out at the mall. The list just goes on and on. And I know they’re very many people who miss her as much as I do. I often wonder where she would have been in life if she had still been alive, and how different my life would be as well,” said an emotional Johnson after thanking cold cases detectives and the genetic genealogists at the lab that helped solve the case.

Detective Scharf says investigators still are not sure exactly sure how Brooks and Koski crossed paths, and say they have more questions about the case.

Tips can be directed to the Snohomish County Sheriff’s Office at 425-388-3845.

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