Possible hacker (wh, spectator mode and some kind of damage hacks\aimtriggers)
https://www.youtube.com/watch?v=yv29EVCO_m8&feature=youtu.be
Vid captured by my friend Medovik. Like you can see on first seconds he knew that Med joined spectator and wrote about it in chat.
Earlier on this server this guy killed from aek from 1 bullet like and with pistols from middle range.