Crime scene investigation protocols involve securing the scene, interviewing witnesses, examining the scene to find evidence, photographing the scene and evidence, sketching the layout, and systematically processing the scene to collect physical and testimonial evidence while maintaining a chain of custody. Proper documentation through notes, photos, sketches and video is important for subsequent investigation and presentation in court. Evidence collection includes obvious items as well as microscopic traces, with each item packaged separately to prevent damage or cross-contamination.