Presumably imms can check whether the dude that kills a guy several times in quick succession was actually being attacked by the one that keeps dying?

Also whether dead dude was part of a group that were all fighting to killer?

Just wondering how one avoids looking like a multikiller if not, other than running away or avoiding the guy's groups altogether.

Imms of a certain level (no idea what level) and up get tons of messages as things happen. So if player A attacks player B, they get a message player A attacked player B. Same with deaths, etc etc. At least this is how it was explained to me back when I was actually in the loop with some immortals several years ago. So if you argue that you didn't start a fight and you did, they can pretty easily know if you are lying. Tribunal immortals can pretty easily track proper wanted flags this same way as well. Hope that helps, and hope the info is proper and current.