Human sexual behavior is a very complex matter that has been the subject of interesting studies throughout history. Sex is understood as the set of somatic, functional and psychic characteristics that distinguish a man from a woman. Sexual instinct, an hereditary derivation, is moderated and repressed by the intelligence and the conscious, in addition to being governed by the social norms of the environment in which the individual relates to others; on the other hand, there are those with behavioral problems that break all established rules. In the catalog of sex crimes in Mexico there are several criminal types: sexual abuse, rape, solicitation, sexual harassment, child molesting, among others, which can be prosecuted when they conjure the legal asset of the subjects of the crime, the typical norm, its material object and normative elements that may determine the unlawfulness and, consequently, the guilt, judicable by the authorship or participation. From a medical-legal standpoint, proving a crime of this nature represents a monumental challenge, because sometimes there isn't physical evidence manifested, and other times the nature of the circumstantial evidence does not help to determine whether or not a crime was committed.