11.2 Crime Scene Documentation, Search Patterns & Practical Security

11.2 Crime Scene Documentation, Search Patterns & Practical Security

AZPOST Comprehensive Examination Focus: Recruits must demonstrate rigorous mastery of the four primary methods of crime scene documentation, the three-stage progressive photography protocol, measuring techniques for crime scene sketches (rectangular coordinates, triangulation, baseline), the selection and execution of systematic search patterns, and practical contamination prevention pursuant to Ariz. Admin. Code R13-4-116(E)(1)(e)(ii).

A crime scene is a dynamic, temporary environment that begins to degrade the moment an incident concludes. Once physical evidence is collected and the scene is released, it can never be reconstructed in its original state. Consequently, thorough, systematic, and courtroom-admissible documentation is mandatory. Peace officers must capture an enduring, objective record of the scene that allows judges, jurors, and forensic experts years later to visualize the environment exactly as it existed when first discovered.

---

1. The Four Pillars of Crime Scene Documentation

Complete crime scene documentation requires four distinct, complementary methods. No single method can stand alone; each serves a specific evidentiary purpose and compensates for the inherent limitations of the others.

                         [ The Four Pillars of Documentation ]
                                           |
      +-------------------+----------------+----------------+-------------------+
      |                   |                                 |                   |
[ Field Notes ]    [ Photography ]                  [ Videography ]        [ Sketching ]
Chronological &    Progressive sequence:            Supplemental overview   Spatial geometry &
contemporaneous    Overall -> Mid-range -> Close-up with natural sound off  exact measurements

1. Contemporaneous Field Notes

Field notes are the foundation of all investigative documentation:

• Timing: Must be recorded contemporaneously—written at the scene as events unfold or immediately thereafter—rather than compiled hours or days later from memory.
• Content: Exact timestamps (dispatch, arrival, clearing), weather and lighting conditions, transient observations (odors, temperatures), names and badge numbers of all involved personnel, exact locations where evidence was spotted, and verbatim statements from witnesses or suspects.
• Legal Status: Under Arizona Rules of Criminal Procedure Rule 15.1, field notes are discoverable by the defense. Officers must never erase, discard, or rewrite original notes. If an error is made, draw a single line through the error, initial it, and continue writing.

2. Forensic Photography

Photographs provide a permanent visual record of the scene, its condition, and physical evidence in their pristine, unaltered state before anything is touched, moved, or marked.

3. Forensic Videography

Videography serves as a supplemental tool to provide a realistic, continuous spatial walkthrough of the crime scene:

• Technique: Recorded with slow, deliberate, smooth camera pans and uniform movements, avoiding rapid zooming or jerky transitions.
• Audio Control: The audio recording feature must be muted or turned off. Unintentional background chatter, personal comments, radio transmissions, or offhand remarks captured on video can result in severe evidentiary challenges, motions in limine, and embarrassment in court.
• Limitation: Video does not replace high-resolution still photography because it lacks the optical sharpness, depth of field, and controlled lighting required for forensic comparison.

4. Crime Scene Sketching & Diagramming

Sketches translate the three-dimensional crime scene into a two-dimensional geometric representation, filtering out unnecessary visual clutter (e.g., wallpaper patterns or wall decorations) to highlight the precise spatial relationships between evidence items and permanent physical structures.

---

2. Forensic Photography Protocol: The Progressive Three-Step Rule

Forensic photography is governed by strict scientific protocols. Snapshots taken at random angles without systematic organization are unacceptable. Officers and forensic technicians must employ the progressive three-stage photography sequence:

[ 1. Overall / Establishing ] ---> [ 2. Mid-Range / Relationship ] ---> [ 3. Close-Up Views ]
  Surrounding environment,           Item's spatial location               Perpendicular 90-degree
  street signs, 360-deg views        relative to fixed landmarks           First WITHOUT scale,
                                                                           Then WITH scale/marker

1. Overall (Establishing) Photographs

• Purpose: Document the entire scene and its surrounding environment, establishing geographic context and territorial boundaries.
• Technique: Exterior shots should include street signs, house/building numbers, adjacent roadways, and pedestrian access corridors. Interior shots require overlapping 360-degree corner-to-corner perspectives of each room, capturing all walls, doorways, windows, and ceilings.

2. Mid-Range (Relationship) Photographs

• Purpose: Establish the spatial relationship between specific items of evidence and fixed, identifiable landmarks within the scene.
• Technique: The photograph must include both the evidence item (such as a shell casing or bloodstain) and an immovable landmark (such as a doorway, fireplace, or corner of a room). This bridges the conceptual gap between the wide-angle overall shot and the close-up shot, proving exactly where the evidence was situated within the larger room.

3. Close-Up Photographs (The Two-Step Rule)

• Purpose: Capture microscopic and macroscopic surface detail of individual evidence items for courtroom identification, forensic comparison, and laboratory analysis.
• Orientation: Must be taken at a perpendicular 90-degree angle directly above the object, ensuring the camera lens is parallel to the plane of the evidence to eliminate optical parallax and perspective distortion.
• The Two-Step Sequence (Critical Exam Rule):
  • Step 1 (Without Scale): Capture the item in its pristine, untouched state before any markers, placards, or rulers are introduced into the frame.
  • Step 2 (With Scale and Marker): Place a standardized forensic scale (such as an L-shaped ABFO ruler) and an evidence number tent directly alongside the item on the exact same plane, then capture the second shot.

[!IMPORTANT] The Photo Log Requirement: Every forensic photograph taken must be cataloged in an official Crime Scene Photo Log. The log records the camera body serial number, lens type, image number, timestamp, exposure settings, direction faced (e.g., "looking North"), and a brief description of the subject matter.

---

3. Crime Scene Sketching & Measurement Methods

A crime scene sketch supplements photography by providing accurate, measurable spatial data that photographs cannot convey due to lens distortion and variable perspective angles.

Rough Sketch vs. Finished Diagram

• The Rough Sketch:
  • Hand-drawn at the crime scene during the actual investigation.
  • Not drawn to scale, but contains exact, verifiable field measurements recorded with steel measuring tapes or laser measurement tools.
  • Contains case information (DR number, date, time, crime classification, address, lead investigator, sketcher's name).
  • Must feature a prominent North-facing compass arrow, a legend/key identifying evidence markers, and the explicit notation: "NOT TO SCALE."
• The Finished (Final) Diagram:
  • Prepared later at the office using Computer-Aided Design (CAD) software or drafting instruments.
  • Drawn precisely to scale (e.g., 1/4 inch = 1 foot).
  • Prepared specifically for courtroom presentation, eliminating rough lines and clutter while preserving identical spatial measurements.

                 [ Common Crime Scene Measuring Methods ]
                                    |
      +-----------------------------+-----------------------------+
      |                                                           |
[ Rectangular Coordinates ]                                [ Triangulation ]
Two perpendicular measurements                             Straight-line measurements from
at 90-degree angles from                                   two fixed permanent points to the
straight interior walls.                                   evidence, forming a triangle.
Best for INDOOR scenes.                                    Best for OUTDOOR scenes.

Measurement Methodologies

1. Rectangular Coordinates Method:
   • Application: Primary method for indoor crime scenes with straight, perpendicular walls.
   • Technique: Two measurements are taken at right angles (90 degrees) from the center of the evidence item to two adjacent, intersecting permanent walls.
   • Example: A fired casing is located 4 feet 2 inches North of the South wall, and 6 feet 8 inches East of the West wall.
2. Triangulation Method:
   • Application: Primary method for outdoor crime scenes or irregular environments lacking perpendicular walls.
   • Technique: Straight-line measurements are taken from the evidence item to two separate, fixed, permanent reference points (e.g., building corner, telephone pole, fire hydrant, survey monument). The distance between the two reference points is also measured, forming a rigid geometric triangle that allows the exact location to be plotted mathematically.
3. Baseline (Transect) Method:
   • Application: Ideal for expansive outdoor fields, roadways, or collision scenes.
   • Technique: A steel measuring tape is stretched straight through the scene between two fixed points (the baseline datum). Perpendicular offset measurements are taken at 90-degree angles from the baseline tape to each item of evidence.
4. Polar Coordinates (Azimuth) Method:
   • Application: Open desert terrain or aircraft crash scenes.
   • Technique: Measures compass bearing (azimuth angle) and line-of-sight distance from a single fixed geographic datum point using a transit or electronic total station.

---

4. Systematic Crime Scene Search Patterns

Crime scene searches must be methodical, structured, and exhaustive. Random wandering across a scene leads to missed evidence, destruction of latent footprints, and cross-contamination. The selection of a search pattern depends upon the terrain, indoor vs. outdoor setting, availability of personnel, and the size of the evidence sought.

[ Strip / Lane ]        [ Grid (Double Pass) ]      [ Spiral (In/Out) ]         [ Zone / Quadrant ]
=======> =======>       =======> =======>               @                       +-------+-------+
<======= <=======       |   |   |   |   |             ( @ )                     |   A   |   B   |
=======> =======>       V   V   V   V   V            ( ( @ ) )                  +-------+-------+
(Open fields/lanes)     (Most thorough outdoor)     (Underwater/bomb)           |   C   |   D   |
                                                                                +-------+-------+
                                                                                (Rooms / vehicles)

Detailed Analysis of Search Patterns

---

5. Contamination Prevention & Practical Security

Forensic integrity is rooted in Locard's Exchange Principle: "Every contact leaves a trace." When two objects come into physical contact, there is a mutual exchange of physical material. The perpetrator invariably leaves hairs, fibers, DNA, or fingerprints at the scene, and carries away dust, fibers, or biological matter. Crucially, this principle applies equally to police investigators.

Personal Protective Equipment (PPE) & Clean Protocols

To prevent introducing foreign DNA or destroying latent traces, investigators must adhere to strict contamination protocols:

• Barrier Protection: Disposable nitrile gloves must be worn at all times. When processing high-sensitivity DNA scenes, investigators must also wear Tyvek protective suits, shoe covers (booties), hairnets, and face masks.
• Frequent Glove Changes: Gloves must be changed between collecting separate evidence items. If an officer handles a bloodstained weapon and then, wearing the same gloves, collects a suspect's cell phone, the officer has committed cross-contamination, corrupting the evidentiary value of both items.
• Equipment Sanitation: Tweezers, calipers, measuring tapes, and forensic markers must be disinfected with a 10% bleach solution or single-use ethanol wipes between collections.
• Prohibition of Domestic Utility: Officers must never use bathrooms, sinks, towels, or telephones at a crime scene. Officers must not smoke, vape, eat, drink, or discard trash within the inner or outer perimeter.

---

6. High-Yield Exam Traps & Operational Application Scenario

High-Yield Exam Traps for Section 11.2

1. The Scale Trap: Close-up photographs must ALWAYS be taken first without a scale, and second with a scale and marker. Taking only a photograph with a scale allows the defense to argue the scale concealed underlying damage or trace.
2. Rough Sketch Accuracy: The rough sketch is NOT drawn to scale, but its recorded measurements must be exact and verifiable.
3. Search Pattern Thoroughness: The Grid search is the most thorough and comprehensive outdoor search pattern due to its 90-degree double-pass methodology.
4. Indoor vs. Outdoor Measurements: Rectangular coordinates are standard for indoor square/rectangular rooms; Triangulation is the standard for irregular outdoor scenes.
5. Videography Audio: Audio on crime scene video must be turned off or muted to prevent capturing extraneous background statements.

Operational Application Scenario

Scenario: Detectives and patrol officers respond to a desert lot in Pima County where a drive-by shooting occurred. Several small .223 cartridge casings are believed to be scattered across a 50x100 foot area of desert scrub and caliche gravel. Inside an adjacent parked vehicle, a victim was struck, leaving blood pooling on the seat.

• Documentation Sequence: The lead detective first takes overall photographs of the desert lot showing street intersections and the mountain backdrop. Mid-range photos establish the vehicle's position relative to the roadway. Close-up photos of bullet strikes on the vehicle's quarter panel are captured: first pristine without scale, then with an ABFO scale and evidence tent.
• Search Pattern Selection: To locate the tiny .223 rifle casings hidden in thick brush, the supervisor selects a Grid Search Pattern. Six officers line up shoulder-to-shoulder, walking North-to-South along 3-foot lanes. Upon completing the sweep, the line turns 90 degrees and walks East-to-West across the identical ground. This double-coverage successfully reveals three partially buried brass casings.
• Measurement Execution: Because the desert lot has no walls, the sketcher utilizes Triangulation, measuring each casing's distance from a marked concrete utility pole and an asphalt roadway culvert edge, recording the measurements on a rough sketch marked "NOT TO SCALE."