grant carried out these duties neatly , exactly and inconspicuously , and though he was carefully and constantly watched he never showed the smallest deviation from the standards required of him , and no weaknesses of character or technical skill it might have been different if he had been required to kill when doing a solo task at the full-moon period , but his superiors , realizing that at that period he would be outside their control , or his own , chose safe dates for his operations .