An autopsy to determine the cause of Peterson's death was scheduled by the Weld County coroner for and the results of the autopsy and toxicology tests were released on September 2, 2015. The medical examiner determined that Peterson died of an accidental drug overdose. According to the coroner's report, Peterson had undergone a hysterectomy shortly before her death and was prescribed Gabapentin for post-surgical pain management. She was taking morphine at the time of her death; according to the report, she obtained the drug from a friend a week before she died. The report noted Peterson had prescription medications present in her system when she died, including drugs for lung and heart disease, anti-psychotics, and an anti-anxiety medication. Opiates and marijuana were also detected in her system. The coroner's report concluded Peterson experienced a "morphine effect" that triggered respiratory failure leading to her death.