MINNEAPOLIS (WCCO) – Human remains that were found near Alexandria in October have been confirmed to belong to the missing Starbuck woman Laura Schwendemann, and authorities say she died of an overdose of methamphetamine.

The Douglas County Attorney confirmed Tuesday she died of a drug overdose, and will charge 21-year-old Nickolas McArdell with concealing her body.

READ MORE: 'She Was A Jewel': Community Holds Vigil For Victim Of Quadruple Homicide

Schwendemann was last seen on Oct. 14 in a Kensington gas station’s surveillance video. Officials said she was with McArdell, a Starbuck resident, at the time.

McArdell initially told investigators he saw Schwendemann get into a car with men he had never seen before, but later admitted he lied. According to a press release from the Douglas County Attorney’s office, McArdell told investigators he and Schwendemann were injecting methamphetamine that evening. He told police he “blacked out,” and couldn’t remember where Schwendemann was or what happened to her that night.

After admitting drug use to investigators, McArdell was arrested for violating his probation for a previous domestic assault charge.

READ MORE: Woman Critically Injured In Minneapolis Shooting

When he heard of the discovery of Schwendemann’s body, McArdell requested to speak to investigators and admitted Schwedemann had overdosed while they were driving. He told investigators he panicked, and concealed her body in a cornfield.

According to the Medical Examiner, Schwendemann died of undetermined causes. Methamphetamine and THC were both detected in her system, but the report said there was no evidence of physical trauma or natural disease.

The Douglas County Attorney says McArdell would’ve been immune from prosecution for the methamphetamine had he called 911 at the time, thanks to a “Good Samaritan” law recently passed by the Minnesota legislature. Instead, he’ll be charged with concealing a body and could face up to one year in prison.

MORE NEWS: Twins, Lynx, And Gophers Take Home Weekend Wins

Schwendemann was a student at the University of Minnesota, Morris.