Abstract
The objective of this study is to analyze the perception of public security professionals in the State of São Paulo regarding crime scene preservation as an essential part of the chain of custody, aiming to promote forensic evidence that is reliable, intact, and trustworthy. To this end, an online questionnaire was conducted seeking to demonstrate the reality experienced daily by police officers at crime scenes, with the objective of providing information that may be used to demonstrate the lack of awareness regarding the importance of a preserved crime scene for maintaining the chain of custody and, consequently, for ensuring the integrity and reliability of forensic evidence in the State of São Paulo. The responses obtained indicate that police officers understand the importance of crime scene preservation for evidence production; however, there is a lack of knowledge and training concerning the chain of custody, its proper compliance, and its practical application, especially among professionals working in preventive policing, resulting in crime scenes that are not adequately preserved. Therefore, it is concluded that, in order to produce forensic evidence capable of significantly contributing to the promotion of justice, measures should be adopted to foster integration among police officers and provide instruction regarding the chain of custody, so that its stages are properly fulfilled and the criminal event can be effectively clarified.