Is it normal to kill a cat

i had some stray cats move into my garage. they were kittens and a mother. most of the kittens were very nice cute and cuddly. but one of them was mean. so it may have been strangled burned and thrown for no reason. i love animals. more than the average joe. but for some reason this one just had a tendancy to piss me off.
I am not admitting to any crimes here.(hypothetical)