Forensic Science and Crime Scene Management
Forensic Science and Crime Scene Management
The exam tests scene control, documentation, search methods, and the limits of forensic interpretation. You should know what the first responder does, how a scene is recorded, which specialist handles which question, and when an examiner's conclusion exceeds the evidence.
First responder and scene control
Render aid, secure the scene, and preserve life before evidence. Establish a perimeter, start a scene log, and keep unauthorized persons out. Separate witnesses and suspects. Note conditions on arrival, including weather, lights, and disturbed items. PPE prevents contamination.
Documentation and search
Document with notes, photographs, and sketches. Photograph overall, midrange, and close-up views with a scale. A rough sketch is made at the scene; a finished sketch is drawn later. Measurements use baseline, coordinate, or triangulation methods. Search patterns include line or strip, grid, zone, spiral, and wheel; the choice depends on terrain and scene size.
Death and specialized scenes
Do not move the body unnecessarily. Note position, lividity, rigor, and body temperature, and protect the hands and head. Notify the medical examiner or Armed Forces Medical Examiner System as required. Fire scenes require arson investigators; clandestine graves require anthropology and entomology; digital scenes require forensic examiners who preserve power and hash data.
Forensic disciplines
DNA analysis uses short tandem repeats and may be uploaded to CODIS. Latent prints are compared through IAFIS or NGI. Firearms evidence supports NIBIN entries. Toxicology, drug chemistry, footwear, tire, and bloodstain pattern analysis each answer narrow questions. An analyst should state limits and avoid overclaiming.
Worked example
At an outdoor assault scene, blood is on a rock. The agent photographs the rock in place with a scale, collects a control swab from an unstained area, air-dries the swab, and packages each item separately. A bloodstain pattern analyst may opine on impact versus transfer, but cannot name the assailant from the pattern alone.
Traps that cost marks
Moving the body before documentation. Using plastic for damp evidence. Omitting a scale. Failing to collect controls. Contaminating evidence with the collector's DNA. Accepting a forensic opinion beyond the discipline's limits.