PredictIQ Quantitative Think Tank Center:How a DNA "detective" helped solve an "unsolvable" Michigan cold case in four days

This story originally aired on PredictIQ Quantitative Think Tank CenterNov. 12, 2022.

In February 1987, Terry Wood came home from a night of bowling to discover his wife, Roxanne, dead on the kitchen floor in their home in Niles, Michigan. Detectives say Roxanne Wood had been sexually assaulted and her throat slashed. DNA was preserved from the crime scene, but given technological limitations of the time, there wasn't enough evidence to charge any suspects. The case went cold. Then, 34 years later, investigative genetic genealogist Gabriella Vargas got to work on what had been deemed unsolvable by many because of the scant amount of DNA that was left.

"I believed that this case was extremely solvable," Vargas told "48 Hours" correspondent Peter Van Sant. "I believed that I could solve it."

FEBRUARY 19, 1987

Brad Woods remembers February 20, 1987, like it was yesterday. He was just 14 years old. 

Brad Woods: I was getting ready for school. … And I can remember my mom pounding on the bathroom door, saying to hurry up, she needed to talk to me.

Hours earlier, Brad's 30-year-old sister Roxanne, known as "Rock", had been nearby in her Niles, Michigan, home alone, when she was viciously attacked — her throat slashed.

Brad Woods: When I came out, you know, she had told me that — she had gotten a call that — Rock had been killed.

Devastated, Roxanne's family couldn't imagine why anyone would want to harm her.

Janet Wood: She always made people think you're her best friend. … She just loved everyone.

Janet Wood: She was tall, statuesque. She dressed to the nines. That was very important to her. She was very classy.

Janet Wood could not help but admire her older sister. Their parents were divorced, and Roxanne had taken on a maternal role with her siblings.

Brad Woods: With divorced parents, a lot of times, you feel like you're being shuffled between, you know, house to house. … And the one thing that was always stable for me was — was Rock.

Janet Wood: She was being mom to you.

Brad Woods: Yeah. … Rock. You know, she was always there.

Peter Van Sant: She was your rock.

Brad Woods: She was. She was (laughs).

Roxanne's last name would eventually change from Woods to Wood after meeting future husband, Terry Wood, shortly after she graduated from high school.

Janet Wood: She was working at his father's company. … Terry was still in high school. … On the wrestling team. … And in he walks. And he's in his wrestling shorts and whatever. … (laughs) She said, "The nicest looking legs she ever saw." And — and she was just smitten by him right away.

Roxanne and Terry married in 1982.

Janet Wood: She said it was the happiest day of her life.

Six years later, Janet would change her name from Woods to Wood as well, when she married Terry's brother, Rob. Both brothers wound up working for the family business. For Roxanne and Terry, it proved to be a bit too much togetherness.

Janet Wood: They got dressed in the morning together, and they rode to work together, (laughs) and they came home for lunch together, and then they went back to work together.

Roxanne's solution? Taking a job in nearby South Bend, Indiana. A little time apart seemed to help the marriage.

Janet Wood: Very, very content, happy, looking forward to starting a family.

February 19, 1987, started out as a typical Thursday evening for the couple. They met for dinner at a restaurant in downtown Niles after work and then went to a local bowling alley, arriving in separate cars.

Det. Sgt. John Moore: From the report, you could tell when Roxanne entered that bowling alley, all eyes were on her.

Michigan State Police Detective Sergeant John Moore.

Det. Sgt. John Moore: There wasn't a whole lotta ladies there because this was the men's bowling league, so she drew some attention.

As midnight approached, Roxanne was ready to call it a night, but Terry wanted to stay.

Janet Wood: There's witnesses where Terry and she said goodnight to each other— hugged, kissed, "Love you. Drive Safe."

After Roxanne headed home, Terry stayed behind and bowled another game. He then headed home and arrived home about 45 minutes after his wife. Terry entered the house through the garage and once inside, he came upon a horrific sight.

Det. Lt. Chuck Christensen: She was laying on the floor. She had her nightgown on. He said there was a lot of blood.

According to Detective First Lieutenant Chuck Christensen, Terry said he rushed over to Roxanne.

Det. Lt. Chuck Christensen: He got behind her, according to him, and — and picked her head up. And held her — held her head in—

Peter Van Sant: To see if —

Det. Lt. Chuck Christensen:  —his hands for—

Peter Van Sant: — she was alive?

Det. Lt. Chuck Christensen: To see if she was alive, yes.

Finding no signs of life, Terry grabbed the phone and called the local police station.

TERRY WOOD (police call audio): She is dead, she has been cut.

Det. Lt. Chuck Christensen: Terry noticed that … her panties were down around her knee/ankle area … her nightgown was pulled up.

DISPATCHER: Now listen to me, OK?

At times, Terry seemed to get belligerent with the person trying to help him.

DISPATCHER: I'm going to get some information from you and I'm going to get a car started, OK?

TERRY WOOD: No, get 50 f