Steeling a life of a human. Can it be "good"?
If it would be done to a carrier of deadly disease which at present moment could be contained only by burning the body otherwise many more will die.
To an inocent relative of a leader commanding army that kills others to lure him out?
To a person who suffers unbearable and untreatable pain and who asks for it.

No matter if you choose to kill or not to kill, in these cases it would be immoral act done with moral intent.