I was recently attacked and killed by a cheater with nomad battleship turrets mounted on a fighter. The cheater had a miner ID and was named something. He/she said "Hey fagot" and "Time to die" Then he/she killed me. I have a screenshot somewhere on my disk where you can see the dialouge.
Besides the dialogue; in order too proof cheating I recommend having Fraps running at all time, then hitting the record and/or screenshot hotkey to get appropiate material.