This guy by the username of SLENDER was aimbotting like hell and he wouldn’t get votekicked because one guy on his team wouldn’t do /y. He got 300 kills in one game. It’s on the babel server. PLEASE perm ban him. Ask anyone who was on the babel server at the time. It happened at 12-31-12 @ 1:42 PM EST time.
Here’s a screenshot of the scores:

Score board isn’t a reliable source of evidence really. Anyone could score 300+ if they try. Hell, I’ve reached over a thousand.

I do suggest you make a screenshot of his accuracy by doing /accuracy (name).
Though not very effective, it would still be much more useful than showing the scoreboard. If the aimbotter is careless, he’d have his accuracy over the hundred marker, hell even a thousand. But to be extremely sure, record a video next time.