Crime Scene Examination Methodology

The tradecraft guide of the step-by-step method used by the general law enforcement community and police detectives to thoroughly and systematically examine crime scenes – to utilize as an operative.

Conducting a crime scene examination is a meticulous process conducted to gather, document, and preserve physical evidence from the location where a crime has occurred. The primary purpose of this examination is to reconstruct the events leading to, during, and following the crime, providing investigators with critical information to identify suspects, understand the crime’s modus operandi, and establish a timeline of events.

This systematic collection and analysis of evidence — ranging from fingerprints and DNA to digital data and trace materials — are crucial for building a robust case that can withstand legal scrutiny and ultimately lead to the apprehension and conviction of perpetrators.

        CRIME SCENE EXAMINATION GUIDE

STEP 1)     Initial Response and Securing the Scene

[Objective]     Ensure the scene is safe and preserve evidence integrity.

Address any immediate hazards such as fires, gas leaks, or potential secondary threats that could jeopardize the scene or personnel. Communicate with first responders to gather initial observations that may be crucial for the investigation. Use body-worn cameras or other recording devices to capture real-time footage of the scene upon arrival, providing an unaltered initial visual record.

Assess the need for additional resources, such as forensic units or specialized teams, to support the investigation from the outset. This thorough and proactive approach ensures that the scene is comprehensively secured and that critical evidence is preserved from the very beginning.

• Arrival:     The first officer on the scene must ensure their safety and the safety of others. This includes checking for suspects, aiding any injured parties, and calling for backup if necessary.

• Securing the Scene:     Establish a perimeter with crime scene tape to prevent unauthorized access. This helps maintain the integrity of evidence and prevents contamination.

• Documentation:     Log everyone who enters or exits the crime scene. This log helps maintain chain of custody and ensures accountability.

STEP 2)     Preliminary Survey and Planning

[Objective]     Assess the scene to determine the scope and develop an action plan.

Evaluate potential hazards such as biohazards, structural instability, or the presence of hazardous materials. Implement necessary safety measures to protect the investigative team. Additionally, consider any environmental factors, such as weather conditions, that may impact evidence preservation and adjust the examination plan accordingly.

This thorough risk assessment ensures that the scene can be processed safely and effectively without compromising the integrity of the evidence.

• Initial Walkthrough:     Conduct a careful walkthrough to gain an overview of the scene. Note any obvious evidence and potential areas of interest.

• Develop a Strategy:     Plan the sequence of activities, determine what resources are needed, and assign tasks to team members. This includes deciding on the types of evidence to prioritize and how to systematically approach the examination.

STEP 3)     Documentation

[Objective]     Create a comprehensive and permanent record of the scene.

Utilize video recording to capture a continuous and dynamic view of the crime scene. This can provide context that still photographs might miss, such as the spatial relationship between pieces of evidence and the overall layout.

Narrate the video to highlight significant observations and direct attention to critical areas, ensuring the recording complements the photographs and sketches.

• Photography:     Take wide-angle shots of the entire scene, followed by closer shots of specific areas and evidence. Ensure photos are taken from multiple angles and include a scale for reference.

• Sketching:     Create a rough sketch of the scene during the initial walkthrough. Later, refine this into a detailed, scaled diagram showing the location of evidence and key features.

• Notes:     Keep detailed notes throughout the process, recording observations, environmental conditions, and any actions taken. Notes should be clear and thorough to aid in report writing and future reference.

STEP 4)     Detailed Search

[Objective]     Methodically locate and collect all potential evidence.

Utilize advanced tools and techniques to enhance the search process. This includes using alternate light sources to detect bodily fluids or fibers invisible to the naked eye, ground-penetrating radar for locating buried evidence, and portable DNA analyzers for immediate biological evidence identification.

Additionally, crime scene technicians can employ chemical reagents like luminol to reveal blood traces that have been cleaned.

These specialized methods ensure a comprehensive examination, allowing operatives to uncover and document even the most elusive evidence that might be crucial to the investigation.

• Search Patterns:     Employ systematic search patterns (e.g., grid, spiral, quadrant/zone) to ensure no area is overlooked. The choice of pattern depends on the size and complexity of the scene.

• Evidence Identification:     Mark evidence with numbered markers as it’s discovered. Avoid touching or moving evidence until it is documented and ready for collection.

STEP 5)     Evidence Collection and Preservation

[Objective]     Collect evidence in a manner that preserves its integrity for analysis.

Pay extra attention to perishable or fragile evidence, such as biological samples or electronic devices. Biological samples should be stored in conditions that prevent degradation, such as refrigeration, and electronic devices should be secured in Faraday bags to block external signals.

In cases involving digital evidence, ensure proper steps are taken to clone devices and preserve original data without alteration. Utilizing these techniques ensures the integrity and reliability of evidence, which is paramount for subsequent forensic analysis and legal proceedings.

• Proper Handling:     Use gloves and appropriate tools to handle evidence to prevent contamination. Use tweezers for small items and avoid excessive handling.

• Packaging:     Each piece of evidence should be packaged separately in suitable containers (e.g., paper bags, plastic bags, boxes). Label each package with a unique identifier, description, date, time, and collector’s name.

• Chain of Custody:     Maintain a detailed chain of custody log, documenting every transfer of evidence from collection to storage to laboratory analysis. This ensures the evidence is admissible in court.

STEP 6)     Final Survey

[Objective]     Ensure completeness and accuracy before releasing the scene.

Conduct a final audit of all collected evidence to verify that each item is properly logged, labeled, and securely packaged. Confirm that all evidence aligns with the documented chain of custody before transporting it to the forensic lab or evidence storage.

• Final Walkthrough:     Conduct a final walkthrough to verify that all evidence has been collected and the scene has been thoroughly documented.

• Cross-Check Documentation:     Review all notes, photographs, sketches, and evidence logs to ensure consistency and completeness. Make any necessary corrections or additions.

• Secondary Review:     Have a second investigator or supervisor independently review the scene and all documentation. This second set of eyes can catch any overlooked evidence or discrepancies in the documentation, ensuring the thoroughness and accuracy of the investigation.

• Environmental Check:     Reassess environmental conditions, such as lighting, weather, and potential hazards, to ensure they have been accounted for in the documentation. Any changes or impacts on evidence collection should be noted.

STEP 7)     Release of the Scene

[Objective]     Officially conclude the on-site investigation.

Conduct a thorough final check to ensure no equipment, materials, or evidence has been inadvertently left behind. This step is crucial to maintaining the scene’s integrity and ensuring that nothing that could impact the investigation remains.

• Coordination:     Coordinate with other investigative units and agencies to ensure all necessary work has been completed.

• Release Notification:     Inform the property owner or responsible party that the scene is being released. Provide instructions for any remaining security or safety measures.

STEP 8)     Follow-Up

[Objective]     Ensure continuity and thoroughness in the investigation.

Maintain regular communication with forensic analysts, legal teams, and other relevant parties to track the progress of evidence analysis and case development. Continuous updates ensure that investigators can swiftly act on new information, adjust their strategies as needed, and provide timely updates to victims’ families and the public.

This ongoing collaboration is essential to adapt to emerging evidence, refine investigative leads, and prepare for potential court proceedings.

• Evidence Submission:     Submit collected evidence to the appropriate forensic laboratory for analysis.

• Report Writing:     Compile a comprehensive report detailing the crime scene examination process, findings, and any relevant observations. Include photographs, sketches, and evidence logs.

• Debriefing:     Conduct a debriefing with the investigative team to review the process, discuss findings, and plan subsequent steps in the investigation.

        TRADECRAFT EXAMINATION

        FBI EXAMINATION

Comparing FBI and police methods of crime scene examination reveals both shared fundamentals and distinct differences driven by scope and resources. Both agencies adhere to meticulous protocols for securing scenes, documenting evidence, and maintaining chain of custody.

However, the FBI often employs more advanced technology and specialized expertise due to its broader jurisdiction and greater resources. This includes access to high-tech forensic laboratories, cutting-edge digital forensics tools, and a wider array of specialized units, such as behavioral analysis teams and counterterrorism experts.

Local police, while highly skilled and knowledgeable about their specific communities, may have more limited resources and rely on traditional investigative techniques and regional forensic labs. The FBI’s involvement is typically reserved for more complex or high-profile cases that cross state lines or involve federal statutes, thus necessitating a higher level of coordination and specialized approach.

Effective crime scene examination requires meticulous attention to detail, systematic procedures, and careful documentation. By following these steps, operatives can ensure that they gather and preserve critical evidence, ultimately aiding in the pursuit of justice or the mission.