Death Threats

So I dont usually post in the community, but I just had a game where a player was obviously upset at the way the game was going (we were losing) and started to flame. Unfortunately this is something we've all come to accept in our games, but this player went and private messaged me after the game with my name and address and told me he was coming to kill me. He immediately unfriended me so i was not able to get any screenshots but i was hoping there is some way to check old chat logs? Anyways i gave him a minor report after the game but this was before the death threat. is there anyway to submit a riot games ticket so that i know that this was resolved? I'm genuinely concerned for other players out there that are more susceptible to this kind of harassment, especially younger children that the game if more geared towards. TL;DR players threatened my life, curious how to report after post game. The players summoner name is Sterinell if there are any GM's that see this