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Police Investigations

+Arriving at the Crime Scene When they arrive, there are 3 tasks to perform:

1. Call and ambulance and assist injured people at the scene.

2. Call in reinforcements to help eliminate any hazards that still pose a risk (bombs, fires)

3. Search the crime scene even if witnesses say the perpetrator has left. They must assume that the perpetrators are present and

armed and must search thoroughly.

+Protecting and Preserving the Crime Scene

Crown’s success in a case depends on the condition of physical evidence; therefore, officers must establish 2 boundaries:

1. Centre – the area in which the offence was actually committed.

2. Perimeter – the surrounding areas where the offender may have been present and left evidence (includes entry and escape routes).

+Why Preserve a Crime Scene: 3 Reasons

1. To allow for a thorough search of the scene

2. To seize and collect physical evidence

3. To ensure that the physical evidence seized is admissible in court.

Note: If evidence at a scene is not handled properly, it can become contaminated. Contamination is the loss, destruction, or alteration of

physical evidence that may no longer be admissible in court or may lead to inaccurate conclusions.

+Protection of Evidence

One way to protect and preserve evidence is to document the scene carefully. Officers keep a police log – a written record of what they have witnessed or learned at the scene.

Investigators use photographs, sketches, and other recording techniques to document the evidence found at a scene.

+Officers’ Roles at a Scene

4 Types of Officers investigate a crime scene:

“Patrol Officer” is usually the first one of the scene. They have a “beat” or an area they patrol regularly. They are to secure the scene and ensure the evidence is not tampered with.

“Scenes of crime officer” is trained in evidence collection and preservation. Skilled photographers, trained in lifting prints, foot, and tire impressions. Also collect blood and hair evidence. Tend to work less serious crimes, such as break and enters

and car thefts.

+Officers’ Roles at a Scene

“Criminal identification officer” is responsible for searching the crime scene, examining, gathering and examining evidence, and sending evidence to the lab for analysis.

“Criminal investigations bureau officer” is a plainclothes detective with experience in areas such as homicide, robbery, or sexual offences. Trained to supervise the investigation, interview witnesses, interrogate suspects, draw conclusions from the physical evidence, and make arrests.