According to a Los Angeles County Department of Medical Examiner-Coroner report dated Dec. 6 and obtained by E! News, traces of cocaine, cannabinoids (a substance found in cannabis plants) and benzodiazepines (a depressant) were detected in the Men in Tree star's system in August when she was admitted to a hospital following a car crash.
However, the coroner's spokesperson clarified that there was no evidence of impairment by illicit substances at the time of the crash.
The cannabinoids were detected in her urine but not her blood sample, which is "consistent with prior use but not at the time of injury," per the coroner. Meanwhile, a test on her blood sample at the hospital showed the presence of benzoylecgonine, an inactive metabolite of cocaine.
A urine test performed after Heche's hospitalization also found fentanyl in her system, though the coroner noted in the report that the amount was "consistent with therapeutic use" by the hospital.
Heche tested negative for alcohol, according to the report.
As E! News previously reported, Heche died of inhalation and thermal injuries sustained in an Aug. 5 car crash, with a sternal fracture due to blunt trauma significantly listed as "significant conditions" that contributed to her death. She was pronounced dead at 53 on Aug. 11, after spending days in a coma.
Per the new coroner's report, Heche's inhalation injuries caused "changes to the respiratory system that decreases the intake of oxygen needed to sustain life," resulting in anoxic brain injury.
"Anoxic brain injury (despite the name) is not the result of physical trauma to the body but is an injury due to lack of oxygen," the coroner wrote. "The sternal fracture she sustained is expected to be painful while breathing when she was in her vehicle, further complicating oxygenation and therefore also significantly contributed to death."
The coroner determined Heche's manner of death as an accident.
The Six Days, Seven Nights actress' body was cremated on Aug. 18, according to a death certificate obtained by E! News, with her final place of burial listed as the Hollywood Forever Cemetery in Los Angeles.
Heche is survived by friends and family, including sons Homer Laffoon, 20, and Atlas Tupper, 13.
In a statement to E! News on Aug. 23, Laffoon—who was recently named the permanent administrator of Heche's estate—said he and his brother chose to bury their mother at the well-known cemetery because it's "beautiful, serene and she will be among her Hollywood peers."
"Most importantly, Hollywood Forever is a living place, where people attend movies and concerts and other events," he continued. "She was our Mom, but the kindness and the outpouring of the past few days reminded us that she also belongs to her fans, to the entertainment community, and now, to the ages."