Flashcards Crime Scene Documentation: Notes, Photos, and Sketches
Crime Scene Documentation and Sketching — Comprehensive Study Notes
Role of officers as investigators
Every officer may act as an investigator depending on the case; documenting what they saw, heard, and what people said about the scene can be required by the nature of the crime.
Early topics: taking notes is essential because memory fades; handwritten notes support later documentation (police reports, incident reports).
Photographs in investigations
Photos let others see what was observed and help recall details that weren't noticed initially.
Cautions: photos can be manipulated (AI, Photoshop); photos do not tell the whole story by themselves.
They are part of the evidentiary chain but must be complemented by sketches and notes to convey full context.
Sketching as a critical skill
Crime scene sketches help convey the scene beyond what photos capture.
The speaker admits limited artistic ability but emphasizes familiarity and competence over artistic prowess.
Sketching is a two-part process: a quick, initial sketch at the scene, followed by more detailed sketches later (potentially aided by software).
Sketches should be accurate and focus on the relationships between objects, not on irrelevant details.
Purpose of a crime scene sketch
Two main purposes:
1) To recreate the scene for someone not present (e.g., other investigators, jurors, or a Hollywood recreation).
2) To provide a permanent, court-admissible record of the scene for later reference.The sketch helps compensate for the two-dimensional limitation of maps and photos; it provides a precise representation of where things were and how they related to each other.
The sketch is part of a permanent record that may be used for testimony later on.
The need for planning before sketching
Investigations are both an art and a science; planning helps prevent being overwhelmed and makes the sketch more accurate.
Before entering a scene, ask: What is my plan? What am I recording? What objects and relationships are critical?
Locard’s Exchange (Locard's principle) will be discussed later; planning acknowledges the exchange of evidence at a scene.
Notes on relevance and focus
Include what is necessary for understanding the scene; avoid irrelevant details.
The complexity of the scene (large rooms, hoarders’ homes, clutter) influences what to sketch; sometimes floor plans help.
Floor plans can be obtained from building websites, city records, or blueprints; use them as a reference where available.
Basic sketching tools and setup
Use pencil for rough sketches (erasable); avoid ink in the initial stage to allow corrections.
Any paper will do in a pinch; more professional setups would involve specific materials.
Include a compass to orient the sketch to true north; most drawings are oriented north unless there’s a reason not to.
A measuring tape is essential for distances; rulers may be insufficient for larger scenes.
The legend is crucial to explain the scale and distances on the drawing.
A rough sketch should be placed in an investigative file with notes and a legend; the original should be kept unaltered and copies may be used for witness interviews.
Planning and distance plotting in sketches
An initial plan helps determine what to sketch and how to measure distances.
Distances must be translated from the real scene to the drawing using a scale (e.g., 1 unit on paper equals X units in real life).
Example of a scale: one possible approach is to use a simple ratio, such as
where is the real length and is the drawing length. Then any measured real distance corresponds to a drawing distance
Legend and scale specifics
The legend explains how measurements on the drawing map to real-world distances.
A common approach is to specify a conversion, e.g., "1 inch on paper = 2 feet in real life" (or any chosen ratio) and note the reference points used for this conversion.
It’s common to describe distances in the legend, not just on drawn lines, to avoid misinterpretation.
Rectangular coordinate method (two fixed points)
Concept: plot an object’s location using distances from two fixed reference points (usually two walls at right angles).
Process:
Draw the room as a rectangle (two fixed points on walls).
Measure the distance from each fixed point to the object along perpendicular lines.
The lines from the two fixed points cross at the object’s location.
Example setup:
Let the left wall be the x=0 line and the bottom wall be the y=0 line.
If the object is 3 feet from the left wall and 2 feet from the bottom wall, its coordinates in the room frame are .
In the drawing, translate these distances using the chosen scale: if the scale is , then the drawing distances are
Practical notes:
The method relies on two fixed, non-movable reference points (usually walls).
The accuracy improves with precise measurement and a clearly drawn two-wall frame.
It’s easy to over- or under-represent clutter; include only relevant objects.
Baseline method
Concept: establish a straight baseline across the space and measure each object’s distance from that baseline.
Procedure:
Draw a straight line across the room (the baseline).
Measure how far along the baseline the perpendicular from the object lands (distance along the baseline).
Measure the perpendicular distance from the baseline to the object.
Representation: the object’s location is given by how far along the baseline and how far off the baseline it sits.
Simple description: the coordinate along baseline (b) and the perpendicular offset (p) determine the object’s position:
Triangulation method
Concept: use angle measurements from fixed points to locate an object by intersecting two or more lines of sight.
Requirements: a compass or a way to measure angles; at least two fixed points.
Indoors vs outdoors:
Outdoors, natural lines of sight are common; indoors, you may need additional tools.
Process:
From each fixed point, measure the angle to the object.
Draw rays from each fixed point at the measured angles.
The intersection of the rays marks the object’s location on the sketch.
Requires careful measurement and clear notation of angles on the legend.
Compass-point/angle-based methods
Similar to triangulation; rely on angular measurements from fixed points to establish line(s) of sight.
Important to record which compass reference was used and how angles were measured.
Cross projection method (overhead or drone view)
A newer method that uses overhead data (often from a drone or elevated view) to coordinate the scene from above.
Can be powerful for outdoor scenes or large interiors if equipment is available.
Requires careful calculation to translate overhead coordinates to the scene coordinates.
Other practical plotting considerations
The baseline, rectangular coordinate, and triangulation methods are not mutually exclusive; investigators may combine methods as appropriate.
For large scenes or outdoor fields, cross-projection or aerial data can supplement ground measurements.
The choice of method depends on the scene, the objects of interest, and the availability of fixed reference points.
Using floor plans and external resources
Floor plans can be extremely helpful when available (e.g., through maintenance sites, real estate sites, or city blueprints).
When possible, locate the original floor plan to anchor the sketch to known dimensions.
Do not skip this step; it can dramatically improve orientation and measurement accuracy.
Equipment and workflow for sketching
Essential tools: pencil, eraser, paper, measuring tape, compass.
Optional tools: baseline markers, string or sighting lines, a ruler, and a protractor if needed.
The process is iterative: start with a rough sketch, then refine measurements and lines as more data is collected.
Plan to keep the rough sketch as part of the investigative record; make copies for witnesses and other investigators, keeping the original intact.
From rough sketch to CAD and high-tech options
In larger departments or with specialized capabilities, rough sketches can be imported into CAD (computer-aided design) software to produce precise, presentable drawings.
CAD stands for .
The investigator inputs numbers and coordinates; the CAD output is a polished diagram.
Advanced technologies exist (e.g., laser scanning, sonic scanners, 3D capture) that can create a detailed model of a room.
Caveat: evidentiary admissibility concerns arise if the evidence is computer-generated without a witness explaining the process; testimony is needed to explain how the data was created and processed.
In practice, technology is evolving; currently, traditional sketches and photographs remain foundational, though scanners and 3D models may supplement them.
Testimony and admissibility in court
Every evidentiary piece must be introduced through a witness who can explain its creation and relevance.
Investigators must be prepared to testify about:
The information contained in the sketch or scene capture.
The conditions under which the sketch was made.
The process used to construct it (tools, methods, measurements).
The cross-examination goal is to assess reliability and procedure; a well-explained process reduces uncertainty and makes cross-examination less intimidating.
The role of photos, notes, and sketches in the investigative record
The combination of photographs, notes, and sketches creates a robust, multi-faceted record of the scene.
Each piece complements the others: photos show what was visible; notes capture observations and witness statements; sketches convey spatial relationships and exact locations.
Team-based practice and the classroom demonstration
A classroom exercise demonstrated two investigative teams examining a scene; in real life, two teams at the same crime scene are unlikely but the exercise illustrates coordination and documentation workflows.
Real-world context and examples mentioned
Floor plans and building layouts can be obtained from local sources (e.g., city data, maintenance sites, real estate portals).
A hoarder-style scene was discussed to illustrate how clutter affects what is sketched and how measurements are approached.
An example scenario about an outdoor field event (described as an urban setting during a hypothetical barnyard bash) illustrated the applicability of external triangulation and measurement in field conditions.
Ethical, spiritual, and practical reflections (Romans 12:9)
Romans 12:9: "Love must be sincere. Hate what is evil. Cling to what is good." This is presented as a guiding message:
Encourage good actions and avoid evil; pursue beneficial activities and personal integrity.
The speaker invites students to pursue good deeds, reflect on personal growth, and rely on higher principles to guide professional conduct.
A brief prayer emphasizes gratitude, focus on honoring God, and seeking strength to resist temptation and stay dedicated to learning and service.
Ethical and practical implications discussed
Bias, honesty, and integrity in recording observations are paramount.
The accuracy and defensibility of sketches rely on transparent methods and the ability to explain the process under scrutiny.
Technological advances may change how evidence is captured and presented; investigators must stay current while preserving the ability to explain traditional methods in court.
Quick reference: key formulas and concepts for note-taking
Scale and conversion between real and drawing distances:
where= real length, = drawing length, = real distance, = drawing distance.
Rectangular coordinate example: for a room with the left wall at and bottom wall at , an object at 3 ft from the left wall and 2 ft from the bottom yields coordinates in the room frame, translate with scale as above.
Baseline method coordinates: representing distance along the baseline and perpendicular offset to the object.
Angles and intersections (triangulation): measure angles from fixed points, draw rays, locate intersection.
True north and orientation: mark the sketch with a compass direction, standard practice is to orient north unless a reason exists to do otherwise.
Summary takeaways
Sketching is a critical, structured practice that complements photography and notes, providing a precise, shareable representation of the scene.
Planning, accuracy, and documentation integrity are essential for court admissibility.
Investigations blend science (measurement, geometry) and art (judgment about what to include and how to represent the scene).
Be mindful of evolving technology while maintaining the ability to explain methods and authorize data provenance in testimony.
Quick questions to test understanding
Why is it important to keep the original rough sketch unaltered and make copies for witnesses?
How does the rectangular coordinate method differ from the baseline method in terms of reference points?
What are the advantages and limitations of using CAD or laser scanning in crime scene documentation?
How do you ensure a sketch remains useful if you later discover additional relevant details?