The Pima County Medical Examiner's Office report released Friday says Adrienne Salinas had marijuana in her system but no other drugs.
Tempe police are investigating the death of the Gateway Community College student as a homicide, but haven't publicly identified any suspects.
Salinas disappeared June 15 and her badly decomposed body was found Aug. 12 in a Pinal County desert wash.
She was seen by her roommates leaving their Tempe apartment in the early morning hours of June 15.
Salinas reportedly had packed a bag and told them she was headed to her boyfriend's home in Scottsdale. He says she never arrived.