MANKATO, Minn. (AP) — Authorities have determined a 16-year-old Minnesota girl whose body was found in a field died of accidental suffocation.

Hannah Olivia of New Ulm was found face down in a field west of Mankato on Nov. 4 and pronounced dead at the scene. She was a junior at Mankato West High School.

An autopsy by the Ramsey County Medical Examiner's Office ruled Olivia's death as an accident. The office says she suffocated due to mud and debris in her mouth and nose. The Mankato Free Press reports that a full summary of the report, including toxicology results, will be released after the death investigation is complete.

The sheriff's department recently forwarded the results of its investigation to the Blue Earth County Attorney's Office.