Hacker

https://www.youtube.com/watch?v=cLogYJooqLA&feature=youtu.be

http://battlelog.battlefield.com/bf4/battlereport/show/1/902615479964727936/517963383/

As you can see from the battle report and in the video this cheater was killing people without a weapon, it shows "killed" in the kill feed when he kills you. The ONLY time this happens is when you shoot an explosive like a barrel or the fire pipes ( Operation Locker ). He was 1 shot killing people. 

https://www.247fairplay.com/CheatDetector/Irvine42