Pinoy Crim
JurisprudenceLaw EnforcementCriminalisticsCrime DetectionSociology of CrimesCorrectional Admin
Practice Exams

Module 8.4: Crime Scene Investigation Procedures

I. The First Responder's Duties

The first police officer to arrive at a crime scene is the first responder. Their actions are the most critical, as they set the stage for everything that follows. The first responder's primary responsibilities are, in order of priority:

  1. Offer assistance to any injured persons. The preservation of life is always the top priority. The officer must immediately render first aid and/or call for medical assistance.
  2. Arrest the perpetrator. If the suspect is still at or near the scene, the officer's next priority is to apprehend them.
  3. Secure the scene. This is the most crucial investigative duty of the first responder. They must immediately establish a perimeter and control access to the scene to prevent the contamination or destruction of evidence.
  4. Detain and separate witnesses. Witnesses should be identified and separated from each other to prevent them from influencing each other's stories.
  5. Make initial notes. The officer should begin taking notes on the condition of the scene upon arrival, the time, weather, and any statements made.
  6. Do not touch or move anything. Unless absolutely necessary for medical or safety reasons, nothing at the scene should be touched or moved until the investigators arrive.

Board Exam Tip: The first responder's most important investigative duty is to secure the scene. While life-saving is the top overall priority, securing the scene is what protects the evidence.

III. Crime Scene Search Patterns

Once the scene is secure and documented, a systematic search for evidence is conducted. The type of search pattern used depends on the size and nature of the scene and the number of personnel available.

  1. Strip (or Lane) Search:

    • Method: Investigators form a line and walk in parallel strips across the search area.
    • Best for: Large outdoor scenes with multiple searchers.

  2. Grid Search:

    • Method: A two-pass strip search. The investigators first walk in horizontal strips and then re-do the search in vertical strips.
    • Best for: Providing a very thorough search of a large area. It is the most methodical and comprehensive search pattern.

  3. Spiral Search:

    • Method: The investigator starts at the center of the scene and moves in an ever-widening spiral (outward spiral), or starts at the perimeter and moves in an ever-narrowing spiral (inward spiral).
    • Best for: Scenes with no clear boundaries or scenes with a single investigator. The inward spiral is generally preferred as it avoids disturbing evidence in the center of the scene upon entry.

  4. Zone (or Quadrant) Search:

    • Method: The scene is divided into smaller zones or quadrants. Each investigator is assigned a zone to search.
    • Best for: Scenes with defined areas, such as a house (each room is a zone), or for searching a vehicle.

  5. Wheel (or Ray) Search:

    • Method: Investigators start at the center of the scene and move outwards in straight lines or "rays."
    • Best for: Small, circular scenes.
    • Disadvantage: Not very thorough and is rarely used.

Board Exam Tip: The grid search is considered the most thorough search pattern.

V. Collection and Preservation of Evidence

This is the final stage of crime scene processing.

  1. Handling: Each piece of evidence must be handled carefully to prevent contamination. Investigators should wear gloves and change them frequently.
  2. Packaging: Each item of evidence must be packaged separately in an appropriate container.
    • Paper bags, envelopes, and boxes are used for most items, especially biological evidence (which needs to be able to breathe to prevent mold).
    • Plastic bags should only be used for items that are not wet.
    • Paint cans or airtight glass jars are used for arson evidence to trap volatile fumes.
  3. Labeling: Every evidence package must be properly labeled with:
    • Case number
    • Date and time of collection
    • Location where the item was found
    • A description of the item
    • The name or initials of the collecting officer
  4. Chain of Custody: The package must be sealed with evidence tape, and the collecting officer must sign or initial across the tape. This begins the Chain of Custody—the chronological written record of everyone who has had possession of the evidence from the moment it was collected until it is presented in court.

Conclusion

Crime Scene Investigation is a meticulous and destructive process. It is meticulous because every step must be done systematically and thoroughly. It is destructive because every action—from searching for evidence to collecting it—alters the original state of the scene. Therefore, it is essential that the process is handled with the utmost care and professionalism. A well-managed crime scene provides the foundation of objective evidence upon which a successful prosecution can be built. A poorly managed scene can result in the loss of critical evidence and the potential collapse of the entire case.

Introduction

The crime scene is the most important and information-rich area in any criminal investigation. It is the place where the crime occurred and where the most valuable physical evidence is likely to be found. Crime Scene Investigation (CSI) is the systematic process of searching for, documenting, collecting, and preserving physical evidence. The manner in which the crime scene is handled from the very beginning can determine the success or failure of the entire investigation. This module outlines the standard procedures followed by law enforcement and crime scene investigators.

Key Learning Objectives:

  • Identify the first responder's duties at a crime scene.
  • Understand the importance of securing the crime scene.
  • Describe the different types of crime scene search patterns.
  • Explain the process of documenting the crime scene (notes, photos, sketches).
  • Outline the general procedure for handling a crime scene from arrival to departure.

II. Securing the Crime Scene

  • Purpose: To prevent the contamination, destruction, or removal of physical evidence.
  • Method:
    • Establish a Perimeter: Use crime scene tape ("POLICE LINE - DO NOT CROSS"), vehicles, or other barriers to create a clear boundary. The perimeter should always be larger than the actual scene appears to be.
    • Control Entry and Exit: Establish a single point of entry and exit.
    • Maintain a Crime Scene Log: Everyone who enters or leaves the secured area must be logged in and out. This is crucial for maintaining the chain of custody for the scene itself.
    • Deny Access: Only authorized personnel (investigators, crime scene specialists, medical examiner) should be allowed inside the perimeter.

IV. Documenting the Crime Scene

Before any evidence is collected, the scene must be thoroughly documented in its original condition. This is done through three methods: notes, photography, and sketches.

  1. Notes: A detailed, running narrative of everything the investigator observes and does. Notes should be taken in ink, and any errors should be crossed out with a single line and initialed.
  2. Photography: Creating a complete and accurate visual record of the scene and evidence. This involves taking overall, mid-range, and close-up photos (as covered in Module 7.13).
  3. Sketches: A hand-drawn diagram that shows the layout of the scene and the location of evidence and other important features. The sketch provides accurate measurements that photos cannot.

These three methods work together. The notes explain the scene, the photos show the scene, and the sketch provides the measurements and layout of the scene.

VI. The General Procedure: A Summary

  1. Initial Response & Scene Security: First responder arrives, handles emergencies, and secures the scene.
  2. Preliminary Evaluation: Lead investigator arrives, is briefed by the first responder, and does an initial walk-through to assess the scene.
  3. Documentation: The scene is thoroughly documented with notes, photographs, and sketches before anything is touched.
  4. Scene Search: A systematic search pattern is used to locate all potential evidence.
  5. Evidence Collection & Packaging: Evidence is carefully collected, packaged, and labeled.
  6. Final Walk-Through and Release: The lead investigator does one final walk-through to ensure nothing has been missed. Once the investigator is satisfied, the scene is formally released.

Important: Once a crime scene is released, re-entry may require a new search warrant. The processing must be done correctly the first time.