Crime Scene Investigation

The Crime Scene – Part One

Introduction

Forensic science fundamentally starts at the crime scene, where physical evidence is collected crucial for forensic examination (Jackson and Jackson, 2008). The crime scene contains tangible links to the perpetrator and victim(s), where traces are left behind and carried away. This is encapsulated in Locard's Exchange Principle, stating, "Every contact leaves a trace," emphasizing meticulous evidence collection and analysis's importance.

Crime Scene Processing

Effective crime scene management and detailed recording of evidence are essential for successful prosecution. Key steps for managing a crime scene include:

• Preservation: Securing the crime scene is imperative to prevent unauthorized access by individuals not involved in the investigation. This can include police detectives, forensic scientists, and medical personnel to maintain evidence integrity.

• Recording: The scene should be thoroughly documented through photography, video, and detailed notes in its original state, including a log of actions taken to provide a comprehensive understanding of any context.

• Search: A systematic and thorough search should be conducted utilizing different searching techniques (grid, spiral, zone) to collect and label all relevant physical evidence.

• Storage: Recovered evidence must be securely stored both pre- and post-examination by the State Forensic Laboratory to maintain the chain of custody, essential for substantiating the evidence’s authenticity.

Operations in Serious vs. Volume Crime

There are key operational differences between serious crimes (e.g., homicide, rape) and volume crimes (e.g., burglary, car theft) (Jackson and Jackson, 2016). Serious crime investigations typically require more personnel and resources, employing comprehensive investigative techniques. Invasive methods may include skull or structure removal for evidence gathering, while volume crimes often utilize non-invasive methods, such as fingerprint analysis from surfaces.

Contamination and Cross-Contamination

Contamination prevention is critical to forensic integrity. Adverse environmental factors can destroy valuable evidence; for instance, wet weather can wash away fingerprints. Restricted access to crime scenes is necessary to prevent contamination from unauthorized personnel. The use of personal protective equipment (PPE) is crucial in avoiding unintentional evidence compromise.

• Example of Cross-Contamination: Accidental transfer of evidence can result in misattributed guilt, where improperly collected DNA evidence may wrongfully implicate individuals.

• Case Study: DPP v Craig White [2011]: Craig White was convicted of murdering Noel Roche, emphasizing the importance of forensic evidence in securing a conviction. The crime involved Roche being shot while in a stolen car. Evidence such as the firearm, fingerprints, and DNA connected White to the crime; however, challenges arose as fingerprint matches could not establish precise timelines.

Evidence Collection Specifics

The careful collection of forensic evidence is vital in establishing links between suspects and the crime scene. Types of evidence, such as fingerprints, gloves, and DNA, require meticulous handling to maintain integrity. Addressing issues surrounding "secondary transfer," where DNA may be found at a crime scene without the suspect’s direct involvement, is crucial for accurate forensic analysis.

Role of the First Police Officer at the Crime Scene

The First Officer at the Scene (FOA) bears the responsibility of preserving evidence, no matter the incident's seriousness (Jackson and Jackson, 2008). Initial actions include:

• Protecting evidence from environmental conditions and actions taken by third parties.

• Conducting initial assessments to prioritize emergencies and ensuring that urgent cases are adequately addressed.

• Calling for additional backup and documenting pivotal details of the crime scene to facilitate further investigation.

Initial Assessment Considerations

During the initial assessment, the FOA interviews emergency callers to gather insights into the incident. This includes:

• Establishing the identities and locations of eyewitnesses and possible suspects.

• Ensuring witnesses are separated to prevent conflation of statements, which could lead to misinterpretation of facts.

Emergency Response and Evidence Preservation

While the primary objective is to save lives, it is equally important to protect physical evidence as much as possible. As the investigation unfolds, documentation of details related to the scene becomes vital. False witness statements can complicate cases, providing additional insights into suspect behavior and motivations.

Scene Protection Techniques

Effective strategies for preserving evidence such as restricting access to the crime scene are essential. Utilizing protective measures like covers (e.g., police hats, tents) can shield evidence from environmental exposure. Vigilance against tampering from unauthorized individuals who might attempt to clean or alter the scene is necessary. Special attention should focus on drains or other potential areas leading to evidence destruction.

Evidence Recovery in Various Crime Types

The evidence recovery approach significantly differs between serious and volume crimes. Serious crimes involve extensive recovery efforts with a substantial police presence and specialized equipment, while volume crimes may prioritize specific key locations, illustrating procedural adaptations based on crime severity.

Cordon and Access Control

Establishing proper cordons around serious crime scenes is critical for maintaining evidence integrity. Detailed logs documenting personnel entering and exiting the scene must be meticulously maintained. Considering evidence recovery in phases and maintaining a Common Approach Path (CAP) for professionals entering the crime scenes is crucial for preserving evidence integrity.

Victim Situations and Evidence Collection

In cases where victims are alive but at risk, appropriate measures must be enforced to safeguard evidence while ensuring the chain of custody is maintained during medical interventions. Balancing the focus on victims' welfare and evidence preservation is critical for the successful prosecution of related cases.