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

SIOUX FALLS, SD (KELO) – Decades after losing a loved one, many families are giving up hope. But investigators can always get the evidence they need to arrest them.

On February 28, 1981, the Sioux Falls Police Department began a decade-long investigation.
Someone had left a newborn boy wrapped in a bloodstained blanket on the edge of a field on Sycamore Avenue.

“An autopsy found the child was born alive and was breathing but slowly succumbed to exposure,” said Matt Burns, Sioux Falls police chief in 2019.

Investigators followed up on the leads but couldn’t find Baby Andrew’s family.

The case went cold.

In 2019, The police enlisted the help of a Virginia laboratory and genealogy sites such as to put the branches of Baby Andrew’s family tree together. “We were able to build on this family tree through old birth announcements, old marriage announcements and the like,” said Det. Mike Webb said at the time.

KELO Theresa Bentaa's Cold Case Murder Baby Andrew John Doe
Theresa Bentaas | 2019

Those clues led her to Theresa Bentaas, a Sioux Falls woman who lived less than a mile from where baby Andrew was found. In February of this year, investigators went to her home and carried out a “garbage collection”.

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

The results indicated that Bentaas was most likely the mother of baby Andrew. In an interview with the police, Bentaas said she was “young and stupid”.

When she drove out of the ditch that day in 1981, she told investigators that she was “sad, scared and ran away and wasn’t smart”.

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