Technology leads to breakthrough in decades-old death of Sioux Falls newborn

SIOUX FALLS, S.D. (KELO) — Decades after losing a loved one, a lot of families give up hope. But at any time, investigators can receive the evidence they need to make an arrest.

On February 28th, 1981, Sioux Falls police began an investigation that would continue for decades.
Someone had left a newborn baby boy wrapped in a blood-stained blanket on the edge of a farm field along Sycamore Avenue.

“An autopsy revealed that the infant was born alive and had been breathing, but had slowly succumbed to exposure,” Sioux Falls Police Chief Matt Burns said in 2019.

Investigators followed up on leads, but couldn’t find baby Andrew’s family.

The case went cold.

In 2019, police enlisted the help of a Virginia lab as well as genealogy websites like Ancestry.com to piece together branches of baby Andrew’s family tree. “We were able to continue to build that family tree through old birth announcements, old marriage announcements and things like that,” Det. Mike Webb said at the time.

Those clues led them to Theresa Bentaas, a Sioux Falls woman who lived less than a mile from the spot where Baby Andrew was found. That February, investigators went to her home and conducted a ‘trash pull.’

They took samples from a water bottle, a beer can and cigarette butts for the crucial DNA link that would lead to her arrest.

The results showed Bentaas was mostly likely to be baby Andrew’s mother. In an interview with police, Bentaas said she was “young and stupid.”

When she drove away from the ditch on that day in 1981, she told investigators she was “sad, scared, and ran away from it and was not smart.”

Now, four decades later, attorneys are preparing for a trial.

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