lawful. if you find caylee marie anthony was killed by casey marie anthony, then you will consid s and deciding if the killing is murder in the first degree or murder in the second degree or manslaughter or third degree felony murder or whether the killing was excusable or resulted from justifiable use of deadly force. the killing of a human being is justifiable homicide and lawful if necessarily done while resisting an attempt to murder or commit a felony upon the defendant or to commit a felony in any dwelling house in which the defendant was at the time of the killing. the killing of a human being is excusable and therefore lawful under any one of the following three circumstances. one, when the killing is committed by accident and misfortune in doing any lawful act by lawful means with usual, ordinary caution, and without any unlawful intent, or, two, when the killing occurs by accident or misfortune in the heat of passion without any sudden or sufficient provocation, or, three, when the killing is committed by accident and the misfortune resulting from a sudden combat if a dangerous weapon