The Malingering, is the attempt to deliberately lie or not, against the fact that one wants to investigate. DSM-IV defines Simulation as production of false or exaggerated physical or psychological symptoms motivated by external incentives. The fact proved will always be (in principle), irrefutable before the lie and is the main point to unmask the lie. The issue of lying and simulation is depending on part of the subject with which we are dealing. Usually the people with higher education, may find that they can more easily omit or lie about the truth of the facts, and may be more time-consuming unmasks them. It is also important to analyze whether the accused is in this situation of hearing (in court), for the first time, or whether he or she is already coming to court other times, as well as determining their individual, personal and professional background. The components of personality, affections and feelings should be analyzed, memory, etc., including psychiatric antecedents, using psychometric tests for possible detection of the Simulation, whichas already mentioned, is difficult to assess and depending on the author and his or her ease or manner in dealing with the lie and manipulation of others. Some of the most widely used examples are the Aggression Questionnaire (AQ), the Risk Checklist of Violence (HCR-20) and the Analysis of Procedural Data, and there should be a greater use of M-FAST and ADI [1-4]. It is of extreme importance in this regard, the development of cerebral imaging techniques for a more accurate validation of the binomialvalidation (Functioning of the brain - behavior). Forensic evaluations should include the history of the current disease, the mental state examination, as well as diagnosis and the observed conclusions.