Well it means “Thou shalt do no murder” - murder is malice aforethought meaning a planned killing of one human by another. God gave us laws and justice for us to carry it out legally in due process; some guy, like this one, went into a home and beat a woman senseless then strangled her. That was murder. His execution was not.
Ex. 22:18 “Thou shalt not suffer a murderer to live.”