Forensic science applies scientific principles and methods to legal problems. Effective forensic work relies on structured approaches to accurately gather and analyze information. A well-established framework in crime scene investigation, known as the “7 S’s,” provides a systematic methodology for processing a scene. This framework guides investigators through crucial steps to ensure the integrity of evidence.
Understanding the Core Principles
The “7 S’s” represent a recognized methodology for crime scene investigation, guiding professionals from initial arrival to evidence preservation. These principles maintain the integrity of a scene and its contents, ensuring thorough and accurate investigations.
The Seven Steps in Detail
Secure the Scene
Securing the crime scene is the initial step to prevent contamination or alteration of evidence. This requires establishing a perimeter to restrict unauthorized access. A log is started to record everyone who enters and leaves the area. The goal is to preserve the scene in its original state, protecting any potential evidence.
Separate Witnesses
Witnesses present at a crime scene should be separated immediately to prevent them from influencing each other’s testimonies. This separation helps ensure that each witness provides an independent account of events, reducing the risk of collusion or altered recollections. Investigators can then gather unbiased information, which helps in forming a more accurate picture of what transpired.
Scan the Scene
A preliminary visual assessment, or scanning the scene, provides investigators with an overall understanding of the area. During this step, examiners identify the primary crime scene and any secondary scenes. This initial scan helps determine where photographs should be taken and aids in planning the subsequent investigative steps.
See to it that photos are taken
Comprehensive photographic documentation is crucial before anything at the scene is moved or disturbed. Investigators capture broad perspectives of the entire scene, medium-range images showing evidence in context, and close-up photographs of specific items. These close-ups are often taken with and without a ruler for scale, providing a visual record that can be referenced later.
Sketch the Scene
Creating a detailed sketch of the crime scene provides a spatial representation of the area and the items within it. This rough sketch includes measurements of objects from two immovable points, along with a legend and a compass direction. A well-executed sketch helps in reconstructing the scene and shows the precise location and relationships of evidence.
Search for Evidence
Systematic search patterns are employed to locate all relevant physical evidence within the secured area. Depending on the scene’s characteristics and the number of investigators, patterns such as spiral, grid, linear, or quadrant searches may be used. These methodical approaches help ensure that no area is overlooked and all potential evidence is identified.
Secure and Collect Evidence
Once located, all identified evidence must be properly secured and collected using specific techniques and procedures. Each item is carefully packaged to prevent damage or contamination, then labeled with details such as case number, item description, and collection date and time. A chain of custody log is initiated, documenting every person who handles the evidence, which is necessary for its admissibility in legal proceedings.
Ensuring Investigative Integrity
Following these principles ensures evidence preservation and maintains investigative integrity. Adherence to these systematic steps prevents contamination and loss of crucial information, contributing to accurate conclusions and supporting the legal process. Failure to follow these steps can compromise an investigation and affect evidence admissibility.