The police have the fundamental role of removing from society those who disrespect it, without affecting others. This work is fascinating, but essentially technical. It requires the ability to gather information and discernment to understand it, as well as writing skills to record it clearly and provide information that assists justice in deciding on the innocence or guilt of a person. "Police, Justice, and Criminality" is a true story of a Civil Police Investigator in the interior of the State of São Paulo, experienced in public service and in the investigation of homicides by a specialized police station. It contains the narrative of some cases that required more effort, as well as the problems faced by police officers in carrying out their duties and the misunderstanding from different institutions within the system. If Justice is that blindfolded woman and the Law is her scale, the Police are certainly the sword she wields.