Who can I contact to report a specific player for tyler1 like behavior and threats?

I was wondering if there is anyway to speak with someone to personally look into another player for his behavior which included, afk'ing because he was called toxic after he berated a teammate horribly for being down a few kills. He constantly boasted his pride in feeding and ruining games for people, and how he has other accounts and doesn't care about minor bans like a low priority queue. And repeatedly threatened everyone else in all chat that we were the toxic players and we were going to be the ones getting in trouble due to his abuse of the reporting system.