How two moms chatting at a water park helped crack a Thanksgiving cold case murder

"48 Hours" and correspondent Peter Van Sant report on the unusual way the murder of a college student was finally solved in a rebroadcast of "Mandy Stavik: The Case No One Could Forget." 

On a sunny Friday afternoon in June 2013, Heather Backstrom and Merrilee Anderson, two mothers who live near Bellingham, Washington, decided to give their young children a treat and take them to Birch Bay Waterslides for some splash and play.  The two women could never have imagined the thunderous impact their small decision that day would have on their community.

Backstrom and Anderson were among a group of moms chatting about their families, their lives and their hometown of Acme, a tight-knit rural area a half hour from downtown Bellingham. Randomly, one of the mothers brought up a notorious case from years ago in Acme — the unsolved rape and murder of a beloved local young woman, 18-year-old Mandy Stavik, a recent graduate of Mount Baker High School.

Stavik had come home from college on Thanksgiving weekend 1989, gone for a jog that Friday after the big Thanksgiving meal, and had never come back.  After an all-out search for three days, her body was found 3-and-a-half miles away near the shore of the Nooksack River by Detective Ron Peterson. Peterson is still emotional when he talks about the case nearly three decades later, because he says Mandy "looked like my daughter."

For the residents of Acme, Mandy Stavik felt like everyone's daughter and her murder changed the very fabric of the town. People were suspicious and afraid a killer was among them.

Investigators suspected that Stavik, who was found nude, had been sexually assaulted. It was the infancy of DNA crime-matching technology, and Detective Peterson had recently gotten FBI training in working with DNA. His training paid off.  Male DNA was found on Mandy.      

Investigators scoured the area for any possible suspects, and 30 men gave saliva samples to have their DNA tested for a match to the evidence left on Stavik.  But investigators came up empty, and the case went cold — though never closed.

Decades later, the tragedy of the Stavik case remained a topic of conversation in Acme.  So, it wasn't altogether surprising that day in the water park that it came up in discussion. It was in the context of, "it's crazy that we still don't know who did it," Backstrom told "48 Hours."

Backstrom and Anderson, who had both gone to Mount Baker High School, but barely knew each other at that point, started chatting as their kids frolicked on the water slides. Backstrom suddenly blurted out, "I know who killed her."  Anderson, stunned at the statement, then replied, "I do too."  Mutually intrigued, the two women told each other stories about their encounters with a local man around the time of Stavik's murder.

Anderson said a man named Tim Bass, another Mount Baker graduate, who was a friend of her husband, stopped by her house one night a couple years after Stavik's death, and knocked on the door. He said he had been out hunting and needed to use the phone.  Anderson was home with her infant son. Bass dialed the phone but Merrilee could hear the "beep, beep, beep" of the call not going through, and she suspected Bass was not dialing a working number and had lied about needing to make a call.

 "So, then he walks through the kitchen and back to my bedroom," Anderson recalled "And he said that he used to drive by our house. And that he had always been in love with me. And wanted to make love to me."  At that moment she was seized with fear — her husband was away, and she was alone with a man she suddenly saw as a predator.  "I kept telling him "'no, no,'" but he kept trying to convince me to go into the bedroom with him," she said.  "Finally — I told him I would call the police and somehow — I don't even remember exactly how, I got him out of my house."

Hearing this story, Backstrom exclaimed that she too had a very uncomfortable experience with the same man, Tim Bass, just months before Mandy Stavik's murder.  She had been only 15 at the time, and Bass was 21.  It was after a softball game, and they were riding in a truck driven by another young man, named Dan, whom Heather later married.  At the time though, they were just friends. Heather sat between Dan, the driver, and Tim Bass in the front seat. 

Bass started flirting aggressively with her.  "He would talk about my eyes and say they were beautiful.  Then he took a pen out of the cup holder and would start rubbing it along my knees," said Backstrom.  She says she was very uneasy, but just played along, knowing that Dan's presence would prevent Tim from getting any more physical.  But the incident always stuck out in her memory, and in the small community, she made a point of trying to avoid contact with Bass.

The two women for years had thoughts that if he behaved toward them in this predatory way, it was conceivable that Bass could have done the same thing to other women—maybe even Mandy Stavik.  But they had nothing more concrete than their own suspicions and never named him to police. 

"I really wasn't ready because we're in a small town.  And to accuse someone of something of we don't know for sure, is a little scary," Anderson said.  But here in the water park, more than two decades later, bolstered by a similar tale from her new acquaintance, Anderson knew it was time to speak up.  She contacted a high school classmate who was a detective with the Whatcom Sheriff's Office and told him of their suspicions about Tim Bass.

What happened from there is a twisty tale of clever and relentless investigation by local authorities; a dedicated prosecutor who came out of retirement to take on the case he had started so many years ago; and the enterprising help of a local woman named Kim Wagner, who provided police with a crucial piece of evidence that finally cracked this seemingly unsolvable case. 

"I wanted to do the right thing for Mandy," Wagner said. Her actions and the assiduous pursuit of the case by so many others in the community finally led to a measure of closure for Mandy Stavik's mother Mary and the rest of the family.  "I absolutely did not think it would ever get solved," Mary Stavik said.