[s1e6] To Protect And Serve -

If you are looking for a guide based on the actual manual often cited in police training (like the book Write to Protect and Serve ):

Focus on gathering specific details at the scene—distinguishing marks, clothing descriptions, and exact statements made by suspects. [S1E6] To Protect and Serve

Detective Williams, who initially closed the case, begins to suspect foul play after realizing the toxicology report was never submitted and the victim's phone was never sent to IT. If you are looking for a guide based