Gabriella Vargas has cracked a Michigan cold case that's been on the books for more than three decades. It took the self-taught forensic genealogist from California just four days to figure out who murdered 30-year-old Roxanne Wood from Niles, Michigan.

Wood was found dead in her home in February of 1987. She had been stabbed to death but authorities were unable to figure out who killed the young woman due to lack of evidence.

Forensic Genealogist Gabriella Vargas Has Never Been to Michigan

Vargas tells 16 News Now that she was just 8-years old at the time of Wood's murder. She's never set foot in the state of Michigan.

“I felt this was absolutely a case that I could solve and I was up for the challenge,” Vargas tells the news outlet. “There was only a very, very small amount of biological fluid that was left behind.”

She notes that three other genealogists turned down the case before it landed on her desk.

Case Cracked in Just Four Days

Vargas admits the odds were against her, but she was able to piece together evidence through genetic sequencing.

“When you take that evidence whether it be blood or semen or whatnot, we can create a profile of who this individual is. But all that profile tells us is all their genetic markers. It tells us if they are male or female, what ethnicity they are, it doesn’t say this is who their person is," Vargas explains in the video below. "We then use that profile in these databases to then build and figure out matches that are related to this individual and then figure out how this individual fits into that family tree.”

Vargas' sleuthing led her to three brothers, one of which was a career criminal. Authorities arrested 67-year-old Patrick Gilham in February. He was sentenced last week to 23 years in prison.

“For me, this was about bringing closure to the family and justice to Roxanne. But this is why I do this, I do this to bring closure to these families,” Vargas says.

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