«Experts at private labs take advantage of public genealogy websites such as GEDMatch, where people submit their DNA to build their own family tree or identify long-lost family members. The idea is to identify an unidentified suspect or victim by matching their DNA with family members who agreed to make it available on the public websites.
In this case, Baby Andrew’s apparent family members were all from Sioux Falls, Webb said.
“We were able to continue to build that family tree through old birth announcements, old marriage announcements,” Webb said. “We started putting the pieces together. We always felt like our suspect must have been a fairly young individual.”
And so they zeroed in on a woman on the family tree who would have been 19 in 1981 — Bentaas.
According to the affidavit, police went digging in her trash to find beer cans and cigarette butts to test her DNA. Sure enough, it was linked to Baby Andrew’s.»