Module 7.13: Forensic Photography & Crime Scene Documentation

I. The Purpose and Principles of Forensic Photography

A. Purpose

The fundamental purpose of crime scene photography is to record the original scene and all physical evidence in their original location and condition, before anything is moved or altered. The photographs should tell a clear and logical story of the crime scene.

B. The Cardinal Principles of Crime Scene Photography

There are two main principles that govern the practice of forensic photography:

Accuracy and Fairness: The photographs must be a true and accurate representation of what was there. They should not mislead or create a false impression. This means:
- No Deletions or Alterations: Nothing should be removed from or added to the scene before it is photographed.
- Proper Lighting and Exposure: The photos should be clear and well-lit.
- Fair Representation: The photos should not be taken at an angle or with a lens that distorts the perspective or the perceived size/distance of objects.
Completeness: The photographic record must be complete. It is a common saying that it is better to take too many photos than too few. The investigator should photograph the entire scene, all evidence, and all approaches and exits.

III. Crime Scene Sketching

A crime scene sketch is a hand-drawn or computer-generated diagram of the crime scene that accurately depicts the location of evidence and other important features. It is a vital supplement to the photographs.

A. Why Sketch if You Have Photos?

Selectivity: A sketch can leave out irrelevant clutter and focus only on the important items.
Measurements: A sketch provides the precise measurements and distances between objects, which a photograph cannot do.
Clarity: It can provide a simple, "bird's-eye view" that is easy for a jury to understand.

B. Types of Sketches

Rough Sketch: A pencil-drawn sketch created at the crime scene. It contains all the necessary information, measurements, and evidence locations, but it is not "pretty."
Finished/Final Sketch: A formal, cleaned-up version of the rough sketch that is created back at the office, often using computer-aided design (CAD) software. It is drawn to scale and is used for courtroom presentation. The rough sketch is still retained as evidence.

C. Information on a Sketch

A proper sketch must include:

A legend identifying the items of evidence.
A compass showing the north direction.
The date, time, and location of the scene.
The name of the artist and the case number.
Accurate measurements showing the location of evidence from at least two fixed points (a method called triangulation).

V. Digital Photography and Chain of Custody

The move from film to digital photography has created new challenges for evidence management.

Chain of Custody: Just like physical evidence, digital images must have a documented chain of custody. This means tracking the image file from the moment it is created on the camera's memory card to the time it is presented in court.
Authenticity: To ensure the images are not altered, the original, unaltered digital files must be preserved. Any adjustments (like brightness or contrast) must be made on a copy of the original image, and all changes must be documented.
Metadata: The data attached to a digital image file (such as the date, time, and camera used) is also an important part of the record.

Introduction

"A picture is worth a thousand words." This is especially true in a criminal investigation. Forensic Photography, also known as crime scene photography, is the art and science of creating a permanent, accurate, and fair visual record of a crime scene and physical evidence. Its purpose is to support the notes and sketches of the crime scene investigator and to provide a visual aid for the judge, jury, and others who were not present at the scene. Effective crime scene documentation, with photography at its core, is essential for the successful investigation and prosecution of a crime.

Key Learning Objectives:

State the purpose and cardinal principles of forensic photography.
Describe the three main types of photographs taken at a crime scene (Overall, Mid-range, Close-up).
Understand the importance of using a photographic scale.
Explain the basics of crime scene sketching.
Discuss the importance of the chain of custody for digital images.

II. The Three Stages of Crime Scene Photography

A systematic approach is required to ensure a complete photographic record. This involves taking three types of photographs, moving from the general to the specific.

1. Overall (or Long-Range) Photographs

Purpose: To show the "big picture" of the crime scene and its surrounding area. They capture the location of the scene and its general condition.
Technique:
- Taken from the outside of the crime scene, showing its location relative to landmarks (e.g., street signs, buildings).
- Photos of all rooms in a house, taken from the four corners of each room to provide overlapping, 360-degree coverage.
- These photos are taken without photo placards or scales to show the scene in its original state.

2. Mid-Range (or Medium-Range) Photographs

Purpose: To show the relationship between items of evidence and other objects in the scene. They "link" the evidence to the scene.
Technique:
- A single photograph will show a piece of evidence in the context of a larger object or a landmark within the scene.
- Example: A photo showing a handgun (evidence) lying next to a sofa (landmark), or a bloodstain (evidence) on a specific wall.
- These photos are also taken without photo placards or scales initially.

3. Close-Up Photographs

Purpose: To show the fine details of individual pieces of evidence.
Technique:
- The camera should be focused on a single piece of evidence.
- This is a two-step process for each item:
  1. First Shot: A close-up of the evidence without a scale or photo placard.
  2. Second Shot: A second close-up of the same evidence, but this time with a photographic scale (a ruler) placed next to it.
The Photographic Scale: Placing a scale next to the evidence is critically important. It allows the viewer to determine the true size of the object in the photograph. Without a scale, it is impossible to know if a photographed footprint is from a child or a large adult, or if a photographed bullet hole is from a .22 caliber or a .45 caliber. The photo must also be taken at a 90-degree angle to the evidence to avoid perspective distortion.

The Three-Step Process Summarized:

Overall: Where is the scene?
Mid-Range: Where is the evidence within the scene?
Close-Up (with scale): What are the specific details and size of the evidence?

IV. Other Forms of Documentation

Video: Can be a useful tool for providing a dynamic walkthrough of the scene, but it does not replace the need for still photography.
Notes: The investigator's running narrative of everything they did, saw, and observed. Detailed notes are the glue that holds all other documentation together.

The Importance of a Photo Log

A photo log is a written record of every photograph taken at the scene. It includes:

The photo number.
The date and time.
A description of the subject of the photo.
The location and camera settings.
This log is essential for keeping track of the photos and is a required part of the case file.

Conclusion

Thorough and systematic documentation is the foundation of a successful criminal investigation. Forensic photography, when done correctly, provides an invaluable, objective record of the crime scene that can be revisited time and again during the investigation and trial. By following the principles of accuracy and completeness and by progressing from overall to mid-range to close-up views, the forensic photographer can create a clear and compelling visual narrative. This narrative, supported by sketches and detailed notes, ensures that the fleeting state of the crime scene is preserved forever for the scrutiny of the justice system.