In this text we try to show how the factors of the development of a human being, not only determine the personality of the subjects, but also how each person uses, shows and acts according to it. Starting from the psychodynamic theory, with authors such as Jacques Lacan and Sigmund Freud, as the basis of our technical explanation, we try to explain in the best way, based on a practical case of our country, how a subject can commit a crime, and how this crime is evidence of a particular personality structure. In Ecuador there are several cases where criminal responsibility must be determined not only in a criminalistic way, but also with criminological techniques, so legal and forensic psychology are essential to allow an understanding of the dynamics of crime and thus show the capabilities of people to have committed the act he is accused of, his dangerousness, as well as the appropriate social rehabilitation processes for each case.