Back in February of 1981, Sioux Falls Police were horrified when they found a full-term newborn baby dumped in a ditch on the side of the road. The infant was wrapped in a blanket, but he was unresponsive. It was later determined that exposure to the elements resulted in the baby’s death. Medical examiners believe the child was left in the ditch alive, but he eventually succumbed to the elements and passed away before police found him.

At the time, investigators couldn’t identify the baby. No suspects were named, and the case slowly went cold. While detectives collected DNA evidence, there wasn’t much they could do with the information.

Now, nearly 40 years later, police have utilized new technological advances to identify the person responsible for the baby’s abandonment. Theresa Bentaas, who is now 57-years-old, was identified as the baby’s mother after police used the DNA samples and genealogical databases to compile a profile. They compared to profile to available information and reached the conclusion that Bentaas was the likely culprit.

It didn’t take investigators long to learn that Bentaas still resided in Sioux Falls. Authorities initiated a search warrant to get the suspect’s DNA. They compared her sample to the baby’s DNA and found a perfect match. Detectives eventually tracked down the child’s alleged father. He was interviewed, but he will not be facing any charges. According to his statement, he had no idea that Bentaas was pregnant back then.

Bentaas, on the other hand, is now facing murder charges. She’s scheduled to appear in court on March 11th.