It takes a lot of hard work and dedication to become a police officer, which is the usual career path for someone who wants to become a forensic crime scene investigator. Once you've become a police officer or detective, you then need to complete additional training in order to be able to work with evidence correctly. In other words, becoming a CSI requires both physical and mental strength, as well as the willingness to learn. So if you're thinking about becoming a CSI, be prepared to put in long hours.