Crime Scene Photography

Purpose of Photography in Crime Scenes

• Document the layout of the crime scene.
• Record positions of collected and uncollected evidence.
• Provide viewpoints of victims, suspects, and witnesses.
• Capture original conditions of evidence at the scene.

Film and Digital Photography

Film Photography

• Composition: Photographic film contains silver halide grains that expose in light.
• Film Speed: Indicates light-gathering capacity.
• Special Film Types:
  • Polaroid Film
  • Infrared Film

Digital Photography

• Mechanism: Uses a light-sensitive microchip capturing light through pixels (picture elements).
• Each pixel records light as an electric charge, forming image data stored on a memory card.
• Resolution: Higher pixel counts lead to better image detail; measured in millions (megapixels).

Cameras

• Types: The most common cameras in crime scenes are Single Lens Reflex (SLR) and Digital SLR (DSLR).
• Features: Allow for accessory use (lenses, flashes, and filters), manual settings affecting image quality (aperture, shutter speed).

Understanding DSLR Components

• Components include lens, reflex mirror, matte focusing screen, pentaprism, eyepiece, focal-plane shutter, sensor.

Lenses

• Function: Bend light to focus on the film/digital chip.
• Types and Focal Lengths:
  • Normal Lens: 50-55mm, ideal for crime scene photographs (half wall area).
  • Telephoto Lens: 100mm or greater, used for magnification.
  • Wide-angle Lens: 35mm, captures more area than normal lenses.
  • Macro Lens: Less than 50mm, for close-up detailed photographs.
  • Multi-purpose Lens: 28-80mm, versatile for different needs.

Aperture and Shutter Speed

• Aperture: Measures diaphragm opening diameter to control light entry, adjusted by f-number. Lower f-numbers = wider aperture.
• Shutter Speed: Duration film or chip is exposed to light, measured in fractions (1/2, 1/4, 1/8 seconds).

Depth of Field

• Amount of area in focus in foreground/background. Smaller aperture (higher f-numbers) increases depth of field.

DSLR Modes

• Auto Mode: Selects f-stop and shutter speed automatically.
• Sports Mode: Higher shutter speed for moving subjects.
• Night Mode: Lower shutter speed for low light conditions.
• Landscape Mode: Higher f-stops improve depth of field.
• Portrait Mode: Lower f-stops decrease depth of field to highlight subjects.

Surveying the Crime Scene

• Illumination Factors: Light amount, angles, use of artificial light, reflectors, filters.
• Tripods: Essential for stability and reducing blur; should have adjustable legs and levels for accuracy.

Crime Scene Photography Log

• Document each photograph taken, including:
  • Case details: number, type, date, location.
  • Photographer details: name, title, camera settings, lighting.

Overview of Crime Scene Photography

• Complete record of crime scene condition; starts with overall scenes, moves to detail.
• Photography Order:
  • Overview: Entire scene and surroundings.
  • Medium-range: Smaller significant areas.
  • Close-up: Detailed objects/evidence

Special Crime Scene Photography

• Night: Use of external lights or painting with light.
• Indoor and Outdoor: Capture entry/exit points, walls, ceilings; GPS for location.
• Specific Scenes: Arson, sexual assault, impressions, bloodstains, and latent prints require specific techniques for best documentation.

Digital Crime Scene Photography

Advantages

• Immediate review of images ensures clarity.
• High resolution (≥ 6 megapixels).
• Digital stitching creates 3D views.

Disadvantages

• Susceptible to manipulation and data loss.

Ensuring Admissibility

• Standard operating procedures, writable disks, separate files for alterations, detailed log, and photographer testimony.

Videotaping Crime Scenes

• Must include overview, medium-range, and close-up footage.
• Narration should be clear, without side conversations.
• Still photographs are necessary alongside video content for quality.

Sketching the Crime Scene

• Rough Sketch: Created on-site, includes dimensions, layout, and object locations.
  • Includes title block, legend, compass, and points of reference.
• Finished Sketch: Refined, drawn to scale; often created using CAD programs for precision.

Review Points

• Master DSLR settings and modes.
• Understand crime scene illumination techniques and photography logs.
• Comprehend the importance of capturing minimum required photographs and special techniques based on crime type.
• Digital photographs have specific legal requirements for admissibility in court.
• Sketches serve to clarify and enhance recorded details at a crime scene.