ALEXANDRIA (AP) - Authorities say the death of a University of Minnesota-Morris student has been ruled undetermined.

A farmer found the body of 18-year-old freshman Laura Ann Schwendemann of Starbuck in a cornfield Oct. 26 in Douglas County. She had been missing for nearly two weeks.

An autopsy found Schwendemann had not suffered any traumatic injuries. But toxicology tests found "a significant presence" of methamphetamine and THC, the substance found in marijuana, in her system.

A 21-year-old man told investigators he and Schwendemann had been driving around on Oct. 14 and injecting meth. He said Schwendemann had overdosed and that he had panicked and concealed her body in a cornfield.

Douglas County Attorney Chad Larson says the man won't be prosecuted for causing Schwendemann's death, since the evidence does not support the charge, but will be prosecuted for hiding her body.