The Daily Beast and TMZ are reporting that HQ Trivia and Vine co-founder Colin Kroll was found dead this weekend in his New York City apartment. He was 35.

According to TMZ, Kroll’s body was discovered this morning after his girlfriend was unable to reach him. Sources tell the publication that they discovered “drug paraphernalia nearby” and suspect that he overdosed.

Kroll was part of the team that founded short-form video platform Vine in 2012, and followed the company when it was acquired by Twitter, and acted as its CTO and General Manager until 2014. That year, fellow co-founder Dom Hofmann left Twitter, and Kroll took over his duties temporarily before he was later fired. He and Hofmann then founded HQ Trivia, which launched last year and went viral. However, the company faced funding issues late last year — Recode reported that venture capitalist firms were wary of investing in the company after reports of Kroll’s behavior at Twitter surfaced, which cited inappropriate behavior towards women.

More recently, HQ Trivia has faced a shrinking user-base, and further complaints about Kroll’s behavior — Recode reported in November that complaints about his workplace behavior were elevated to the company’s board of directors prior to his promotion to CEO this summer, although the company said that its “investigation yielded no concerns.” The company has been working to expand its offerings, and in October, launched a new game, HQ Words.

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. — Rus (@rus) December 16, 2018

HQ co-founder Rus Yusupov tweeted a confirmation, and a spokesperson for HQ Trivia issued the following statement:

“We learned today of the passing of our friend and founder, Colin Kroll, and it’s with deep sadness that we say goodbye. Our thoughts go out to his family, friends and loved ones during this incredibly difficult time.”

Updated December 16th, 2018, 2:37PM ET: Updated with statement from HQ Trivia.