I would handle the situation by starting the F1, going to the reporter, bringing the reporter to a roof, asking what happened, and who did what, checking logs, going to reported user, bringing him to roof with reporter, and then do the following :
I would ask Player X for his side of the story, then ask for Player Y side of the story, if the stories don't match, I would ask for proof, if valid proof was provided, I would warn Player Y for RDM.