The autopsy and toxicology report released Wednesday by the Weld County Coroner's Office concluded that Peterson, 43, ingested a friend's morphine medication for unspecified pain a week before her death, The Greeley Tribune reports (http://bit.ly/1L6zl9e ).
Doctors didn't find recent morphine prescriptions for Peterson. But she had been prescribed multiple medications for lung and heart disease. She was also prescribed Gabapentin after a recent hysterectomy.
The coroner's office found high levels of Gabapentin in her body but concluded Peterson died from respiratory depression because of a morphine overdose.
The Greeley, Colorado native was found dead July 5 at her apartment by herself.
Peterson appeared in her last film, "Windrunner," in 1994.
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