i think the way they report bodys is that the bodys have a radius around them if a ai walks around them for a second that ai stops walking for a second and the game automatically calls a meeting
than for the knowing who killed or guessing part its more was red around. i honestly think the way it knows if your around is that they can see further than your screen allows to and if you were around the visible light area (that light that goes around corners when you move) then its you why i think it can see more is because of how sometimes it will vote you even tho that crewmate wasnt visible on your screen
also i have noticed that sometimes the people they vote when theres nobody the reporter saw are either self report (happens when absolutly no crewmates were around) or if someone was around the person who reported its them that gets voted of but if you even a little bit were around then they will vote you instead of the others
also im pretty sure that the odds of there being no one who gets voted off is more of a 1/2 or 1/3 when your not around this chance only happens if you werent in the view of the reporter