DNA technology, not available back in 1981, helped investigators close the cold case into the death of Baby Andrew John Doe. Modern science, combined with old-fashioned detective work, led to Theresa Bentaas’s arrest.
Investigators back in 1981 had the forensic foresight to save blood DNA from Baby Andrew John Doe.
“So that if we do have a suspect at some later time, we could match this blood-type against that person and see if they could be the possible parent,” Minnehaha County Coroner Dr. Richard Schultz said back in 1981.
That parent would emerge 38 years later through a series of DNA breakthroughs and dead ends.
“These cases are very frustrating, disappointing, I think you’ve got to learn you’re going to have more failures than successes,” Detective Michael Webb of the Sioux Falls Police Department said.
The DNA search ramped-up in 2009 when Sioux Falls Police worked with researchers from North Texas University to examine evidence from Baby Andrew.
“The problem in this case is the rules of DNA, we were checking a database against we didn’t know who, “Webb said.
Police enlisted the help of another lab in Virginia as well as genealogy websites like Ancestry.com to piece together branches of a family tree.
“We were able to continue to build that family tree through old birth announcements, old marriage announcements and things like that,” Webb said.
Homing-in on suspect Theresa Bentaas, investigators conducted what’s known as a “trash pull” in February. They took samples from a water bottle, Coors Light beer can and cigarette butts for the crucial DNA link that would lead to her arrest.
On Monday, police received DNA test results from a swab taken from inside Bentaas’s cheek. According to an affidavit, the results showed she was mostly likely to be Baby Andrew’s mother.