Modus operandi (approximately translated from latin as "method of operation"; often shortened in English as M.O.) is a term which extensively used in the context of criminal investigations to refer to a number of personal habits of a criminal (including rapists and killers), which form recognizable pattern each time he commits a crime. Dexter's modus operandi served not only to maximize the satisfaction he derives from his victims as all serial murderers do, but to minimize (if not eliminate) any forensic clues and evidence, and to ensure that he did not target innocents.