Crime Scene procedures and search methods:
A preliminary survey is a crucial first step in the investigation of a crime scene to ensure that all necessary steps are taken before the actual processing of the scene begins. The following steps are typically involved:
Arrival at the crime scene:
The first responder ensures that the scene is safe and secure for all personnel involved. This includes preventing unauthorized individuals from entering the area.
Assessment of the crime scene:
A preliminary assessment is conducted to determine the size, nature, and scope of the crime scene. The lead investigator evaluates the layout and the areas that need to be prioritized for evidence collection.
Establishing the boundaries:
The boundaries of the crime scene are defined and clearly marked. This involves setting up physical barriers or tape to prevent contamination of the scene.
Initial walkthrough:
The investigator conducts an initial walkthrough of the crime scene, often without disturbing any evidence, to get an overview of the situation. This helps identify potential evidence, victim locations, and any immediate threats (e.g., hazards or dangers).
Developing a crime scene processing plan:
A detailed plan for how the scene will be processed is developed. This includes selecting the appropriate search method (e.g., grid or spiral), determining the roles and responsibilities of each team member, and identifying key areas for evidence collection.
Recording the scene:
The scene is recorded in its original state using photographs, sketches, and notes. This ensures that the evidence is preserved in its current condition and allows investigators to document any changes made during processing.
Environmental conditions:
Environmental factors such as lighting, weather, and potential contamination risks are assessed. Conditions that may affect evidence (e.g., biological or trace evidence) are taken into account.
Assessment of witnesses and suspects:
Initial questioning of witnesses and suspects is conducted to gather information. Statements are often taken to support further investigation, and their locations relative to the crime scene are documented.
Identification of potential hazards:
Any biological or environmental hazards (e.g., bloodborne pathogens, chemicals) are identified, and appropriate safety measures (e.g., protective clothing, decontamination) are put in place.
Documentation of the search process:
An initial report is generated that outlines the steps taken during the preliminary survey, the state of the crime scene, and any initial findings.
2. Describe the difference between a Grid search method and a Spiral search method. In your answer, state for which environment each search method is most appropriate [25 marks]
Grid Search Method:
Description: The grid search method involves dividing the crime scene into a series of smaller, manageable areas. Investigators systematically search each area in a parallel pattern, and once a full pass is made in one direction, the search continues perpendicular to the first pass to ensure no areas are missed. The grid is often a double search that covers the same area from two directions.
Most Appropriate Environment: The grid search method is most appropriate for large outdoor crime scenes or areas with a lot of ground to cover, where the crime scene is spread out. It is especially useful for locating trace evidence or small items that may be easily overlooked.
Spiral Search Method:
Description: The spiral search method involves starting at a central point and gradually expanding the search in a circular or spiral pattern. The investigator works outward from the center of the scene or inward if searching for a specific point of interest. This method is particularly useful when the starting point of the evidence is known or when the evidence may have been moved along a particular path.
Most Appropriate Environment: The spiral search method is often used in confined or limited spaces, such as indoor environments or crime scenes with a specific focal point (e.g., a victim's body). It is well-suited for areas where the investigator needs to ensure a focused and systematic search around a central location.
3. Crime scenes must be processed using defined procedures to ensure any evidence recovered can be used in a court of law. Outline how crime scenes are secured, recorded, and searched with reference to search warrants, safety, and chain of custody. [40 marks]
Securing the Crime Scene:
The first step in processing a crime scene is to secure the area to prevent contamination and preserve evidence. This includes:
Securing the perimeter: Law enforcement officers establish a physical barrier around the scene to prevent unauthorized access. Crime scene tape or other measures are used to mark off the boundaries.
Restricting access: Only authorized personnel (e.g., crime scene investigators, officers) are allowed to enter the scene. All others, including potential witnesses or suspects, are kept away.
Initial assessment and safety measures: Investigators assess the scene for potential hazards (e.g., biological materials, chemicals). Appropriate personal protective equipment (PPE) such as gloves, masks, and protective clothing is worn to prevent contamination of both evidence and personnel.
Search Warrants:
A search warrant is required for most crime scene searches to ensure that evidence gathered is admissible in court. The search warrant is obtained from a judge based on probable cause that evidence exists at the scene.
Exceptions to search warrants: In emergency situations, or if consent is given, a search may proceed without a warrant. Additionally, a search may be conducted during an arrest if there is immediate need to secure evidence.
Recording the Crime Scene:
Proper documentation is crucial to maintain the integrity of the investigation:
Photographs: The entire scene is photographed from various angles, with particular focus on evidence, body positions, and the overall layout. Close-up photos of individual pieces of evidence are also taken.
Sketches: A crime scene sketch is created to show the layout of the scene, including the location of evidence. It serves as a visual representation for later analysis and court presentations.
Notes: Investigators record detailed notes about the scene, including the time of arrival, conditions, and specific actions taken during the investigation.
Searching the Crime Scene:
After securing and documenting the scene, the next step is to conduct a thorough search for evidence. Search methods like the grid, spiral, or strip search methods are used depending on the environment.
Evidence is collected systematically, with each piece carefully documented, preserved, and tagged.
Chain of Custody:
The chain of custody ensures that evidence remains uncontaminated and can be linked to its origin and handling. This involves:
Detailed records of who handles the evidence: Every person involved in the handling, transport, or examination of evidence must document their actions.
Signature and receipt system: Each item is accompanied by a signature upon receipt and transfer to another person. This ensures that there is a clear trail of custody.
Minimizing handling: Best practices dictate that as few people as possible handle evidence to reduce the risk of contamination. Each person involved is a potential witness in court and may be called to testify about the evidence's handling.
Safety Protocols:
Biological hazards: Special attention is paid to the handling of biological specimens. Crime scene investigators are often vaccinated (e.g., against Hepatitis B) and wear protective gloves, footwear, and in some cases, liquid-repellent overalls.
Other hazards: Investigators are also trained to recognize and mitigate dangers like toxic chemicals or unstable structures. They may use masks if exposed to infectious dust or when scraping dried blood from surfaces.