In the picture below you will see I d to kill a player in spawn zone, I don't know the exact reason for this happening, but I think the server gets a bit confused when players lag, so it might see the player as a monster or something.
If I encounter this bug again and can see an obvious reason I will update this topic. 
Downloadable Images:
ok, thank you for the help
pocadmin, I've narrowed what I think the cause may be to 2 things, when you go in front of a monster once a player is killed the system gets confused and thinks that you are the monster, as you are the element closest, but not sure how it's made up, so can't say for certain.....
Or like I said before, mass lag as low as 8 fps may allow you to kill.
Kieranb, this picture can't prove that you killed a player in the spawn zone. And tecnically this is not possible.
We are working on the game performance now to increase the game speed and decrease lags.