Multi accounts to evade disciplinary action

Normally i just resort to using the in game reporting system, but in this extreme case i believe it would be appropriate for serious action to be taken into consideration against a player who displayed pure malicious behavior and mental attitude.

I'm enjoying playing ranked games and take them very serious. At the start of my game a team mate commented on our Ryze top's uncommon summoner spells. After which he stated something alone the lines of, "oh sorry guys i plan on just running it down this game" I realized he was not joking when he died 5 times in the first 5 minutes. I figured he must be getting back at a team mate who he had bad experience with in past games, but later found out it was a player not even in our game who upset him and was causing him to sabotage my game. And he felt it would be of no consequence because if any action taken is against his account he would just play on his "other" account.

As a paying customer who would like to enjoy ranked games and keep them competitive and serious I really hope RIOT can address this problem of criminal players simply changing accounts to evade any consequences for their actions.