▶ Watch Video: Sneak peek: The “Unsolvable” Murder of Roxanne Wood

Gabriella Vargas is a self-proclaimed “pink-haired, tattooed mom from California who enjoys woodworking and gardening.” She also happens to be one of the most talented investigative genetic genealogists in the world, according to the investigators she worked with. When the 34-year-old Roxanne Wood cold murder case came across her desk in April 2021, “it was deemed unsolvable prior to my involvement,” Vargas said.

Vargas was confident she could solve this cold case – and fast – finally bringing justice for Roxanne Wood’s family. “48 Hours” correspondent Peter Van Sant takes viewers inside the haunting case in “The ‘Unsolvable’ Murder of Roxanne Wood” airing Saturday, November 12 at 10/9c on CBS and streaming on Paramount+.

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 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. 

Janet Wood

In February 1987, Roxanne Wood and her husband, Terry Wood, went out for a night of bowling with friends. Roxanne left the bowling alley early to return home so she could rest up for work in the morning. But then a man entered her home through an unlocked door. He sexually assaulted her, grabbed a filet knife from Roxanne’s own kitchen drawer and slit her throat. Terry returned home 45 minutes after his wife to find Roxanne dead.

Even though witnesses placed Terry at the bowling alley at the time of the murder, he was immediately considered a suspect.

Investigators found DNA at the crime scene and a sample was preserved. But given the limitations of technology in 1987, not much could be done with it. Terry continued to live under a cloud of suspicion in the community.

As DNA technology evolved, that sample was eventually able to be uploaded to CODIS, a national criminal DNA information repository, in 1999. But no match was returned from that database. As disappointing as that was, everyone was hopeful that the DNA would at least clear Terry when it was tested against his. The result? It wasn’t Terry’s DNA.

After that, the case offered no new leads until 2020.

In order to solve the mystery faster, investigators needed a way to quickly search through the massive case file. They enlisted a group of students from Western Michigan University to digitize approximately 3,500 pages of reports, notes and information into a searchable database.

Around the same time that the students began crunching data, investigators decided to test the DNA one last time. They hired Identifinders International — a company that specializes in genetic genealogy — to examine the tiny amount of DNA left from the crime scene.

“We found out there was, what I would call, a gnat’s eyebrow of DNA left. About 3% of what we normally use,” said Colleen Fitzpatrick, president and founder of Identifinders. “That was the lowest amount of DNA we’ve ever had to work with to solve a case.”

Gabriella Vargas, pictured with Ari, a Goffin’s cockatoo, is a self-proclaimed, “pink haired, tattooed mom from California who enjoys woodworking and gardening.” She also happens to be one of the most talented investigative genetic genealogists in the world, according to the investigators she worked with.

CBS News

Identifinders spent about 10 months working with the data the sample produced, but came up empty.

“It really did feel impossible,” said Fitzpatrick.

Then, one day in April 2021, Fitzpatrick happened to be chatting with investigative genetic genealogist Gabriella Vargas, who worked as a consultant for Identifinders.

“And I said, ‘Well, why don’t you let me look at it?'” said Vargas. “I concluded that I did not stand with the others. I believed that this case was extremely solvable. And I believed that I could solve it.”

So, Vargas got to work. She was able to generate a genetic profile from the suspect’s trace DNA. This genetic profile provided a plethora of information valuable to nailing down a suspect, like where their ancestral origins come from and what race they are.

Once she had the genetic profile, Vargas turned to GEDmatch, an online database where people can upload their DNA results in the hopes of finding more relatives after using consumer sites like 23andMe and Ancestry.com. Users can opt into law enforcement matching, which can allow investigators like Vargas to find matches for their suspects.

Using the results from GEDmatch, Vargas was able to build out the family tree of Roxanne’s killer, going as far back as 1797.

“Essentially what we’re looking for amongst these matches are where they connect to each other. And it led me to a union couple,” said Vargas.

A union couple is where two sides of a family tree meet. This couple was born around 1920, and based on that, Vargas could presume that they would have kids around 1940 or 1950. Thus, the suspect would have to be one of their three sons.

Vargas immediately notified law enforcement of her findings. Investigators conducted background checks on all three sons and eliminated two of them as suspects. The last had a criminal history and had served time for unlawful deviant conduct.

Investigators had their suspect, and his name was Patrick Gilham. But before an arrest could be made, they had to be sure Gilham’s DNA matched the DNA left at the crime scene.

Investigators surveilled Gilham for days, learning his habits and traffic patterns. They even followed him to a laundromat where an undercover trooper collected Gilham’s discarded cigarette butt to be tested for DNA.

The DNA came back from the lab as a perfect match to the crime scene DNA, and Gilham was arrested in February 2022. He was questioned by police for over five hours and insisted he did not remember murdering Roxanne. He said that only a monster could do such a thing.

Gilham later pleaded no contest to second-degree murder and was sentenced to a minimum of 23 years in prison.

Gabriella Vargas, who cracked this ice-cold case in just four days, hopes this innovative investigative technique can help other families in search of justice.

“It’s an honor to be able to work these cases to bring justice to these victims and closure to these families,” said Vargas. “And I will never stop. If anything, I’m more determined now to solve as many cases as I can.”