The actor Michael K. Williams died of an accidental overdose that included the synthetic opioids fentanyl and p-fluorofentanyl, the New York City medical examiner's office said Friday.
Williams, whose work on HBO's "The Wire" and "Boardwalk Empire" was widely praised, died Sept. 6 at age 54. He had been open about his struggles with drug use.
The New York City Office of Chief Medical Examiner said Williams had in his system cocaine and heroin, as well as the synthetic opioids. Fentanyl can be 50 times more potent than heroin, although some heroin users seek it out for just that reason.
A short statement from the medical examiner's office read: "Cause of death: Acute intoxication by the combined effects of fentanyl, p-fluorofentanyl, heroin and cocaine. Manner of death: Accident."
Fentanyl and opioids have been blamed for the record number of overdose deaths in the United States last year— more than 93,000.
Williams, a five-time Emmy Awards nominee, talked about his issues with drug use and getting clean in a 2012 interview with Inside Jersey magazine. "'Why me? Why did I get spared?' I should've been dead," he said.
This story first appeared on NBCNews.com.