A police source was quoted as saying cocaine and heroin were believed to be involved.

Kroll was only named CEO of the HQ Trivia mobile game show app three months ago, replacing fellow co-founder Rus Yusupov who moved over to serve as chief creative officer. Prior to taking the CEO role Kroll served as HQ's CTO. He co-founded the startup in 2015, a few months after moving on from Vine - the Twitter-owned short video format startup which got closed down in 2017.

Kroll’s Vine and Trivia HQ co-founder, Rus Yusupov, posted on Twitter.

“So sad to hear about the passing of my friend and co-founder Colin Kroll. My thoughts & prayers go out to his loved ones. I will forever remember him for his kind soul and big heart. He made the world and internet a better place. Rest in peace, brother”, he tweeted.

Kroll was being mourned on Sunday as a brilliant technology entrepreneur. But he also had a controversial side and had admitted being fired in the past for bad management and for some inappropriate behaviour towards women in the workplace.

It's not clear who will take over the CEO role for HQ Trivia at this stage but Yusupov looks a likely.

Kroll started his career as a software engineer at Right Media, which went on to be acquired by Yahoo in 2006. From then until 2011, he led the engineering team in Yahoo's search and advertising tech group before joining luxury travel site Jetsetter as VP of Product -- where he went on to be promoted to CTO. In 2012 he left to start Vine with co-founders Dominik Hofmann and Yusopov.