SIOUX FALLS, S.D. (KELO.com) — The Sioux Falls woman accused of abandoning her newborn baby 40 years ago has changed her plea from innocent of murder to guilty of manslaughter.

Theresa Rose Bentaas, 60, was charged with first and second-degree murder in the 1981 death of Baby Andrew.

With the guilty plea to manslaughter, the murder charges are dropped.

A motorist found the newborn, which had died from exposure, wrapped in a blanket in a ditch in east Sioux Falls.

The case was cold for decades until advances in DNA testing.

Bentaas’s sentencing hearing is scheduled for December 2nd.