According to the autopsy results, Kroll died of "acute intoxication due to the combined effects of fentanyl, fluoroisobutyryl fentanyl, heroin, and cocaine".

Kroll, 34, was found dead in his SoHo, Manhattan, apartment on December 16, 2018.

Police responded to a 911 call for a welfare check at the Spring Street apartment where they found Kroll unconscious and unresponsive in a bedroom of the apartment.

Kroll was tthe chief executive of HQ Trivia, a phone-based trivia platform, in September. Prior to that, Kroll co-founded Vine, the popular short-form video service bought in 2012 by Twitter. Vine was dropped four years later.

HQ Trivia said: "We learned today of the passing of our friend and founder, Colin Kroll, and it's with deep sadness that we say goodby."

HQ Trivia said in a tweet following Kroll's death: "Our thoughts go out to his family, friends and loved ones during this incredibly difficult time."