Severe Verbal Abuse

So...I'm not sure how the system works but I know that nobody reported this one guy. (I don't want to be calling out names here, so let's call him Bob).

Early game I got into a little argument with them because we had a miscommunication, and we later on in the same game got along quite well. Until the end of the game where he started making death threats and giving me grief for no reason at all. If somebody could help me with how I could get my hands on some chat logs? I could block out the names and put what they said post game. And of course their friend wouldn't report because they were in the duo together. Just a thing that should probably be taken care of. I'm not going to tell Riot how to do their job, but is there some way that I could some chat logs for proof?