Brian Tarantina -- who recently played Jackie in Amazon's "The Marvelous Mrs. Maisel" -- died of "acute intoxication by the combined effects of fentanyl, heroin, diazepam and cocaine," the New York City Medical Examiner's office said.

source https://www.cnn.com/2019/12/18/us/marvelous-mrs-maisel-brian-tarantina-cause-of-death/index.html