Walking Dead?????

I was playing S&D downtown Knife only

And some guys was walking dead or was invisble




As you can see he still has Hp (27)
SO hes not dead
His body was on the floor and he was moving
but you couldnt see him
Like he was invisble
I wish i had the video but i didnt save it
People were not able to see/Kill him

Is this a bug or hack
Becaues this isnt the first time i have seen this
So z8games fix it Quick and fast ;0