CNN reported on Friday that The Wire actor Michael K. Williams reportedly died of an “acute intoxication by the combined effects of fentanyl, p-fluorofentanyl, heroin, and cocaine.” The report came from the New York City Medical Examiner’s Office.

William was found dead earlier this month in his Brooklyn penthouse. His death was deemed accidental in nature according to a statement by the office on Friday. The actor was 54 years old.

Williams had previously opened up about struggling with substance abuse in a 2017 interview with The New York Times.

Williams is best known for his performances in Lovecraft Country, The Wire, and Boardwalk Empire. His other credits include F is for Family, Bessie, and The Night Of. He was nominated for Outstanding Supporting Actor at this year’s Emmy for his role as Montrose Freeman in Lovecraft Country. He was set to appear in the upcoming George Foreman biopic, directed by George Tillman, Jr. (The Hate U Give). He was set to play Foreman’s trainer and mentor, Doc Broadus.

The news of William’s death came with heartfelt tributes from loved ones, friends, and former co-stars including Neicy Nash (Claws), Wendell Pierce (The Wire), and Aldis Hodge (One Night in Miami). The Wire co-creator David Simon wrote a tribute to Williams in The New York Times, describing him as one of the most dedicated actors of our age.

Williams received a tribute at this year’s Emmy Awards during the “In Memoriam” tribute. The tribute ended with a quote from Williams: “The only way for me to say thank you is by making sure that the foundation that I am standing on is strong enough to support the next person that will stand on these two shoulders.”