Starting a Police Investigation

Law 120

Arriving at a Crime Scene

 The location or site where an offence takes place is referred to as the crime scene. When officers arrive, they have three tasks to perform: 1.

2.

3.

Call an ambulance and assist any injured people at the scene.

Call in reinforcements to help eliminate any hazards that still pose a risk (i.e. fire, bombs) Continue to search the scene even if witnesses says perpetrators have left  To protect people at the scene police must proceed as if the perpetrators are still there and armed until they search the area themselves and declare it safe

Protecting / Preserving the Crime Scene

  The Crown’s success in prosecuting offenders often depends on the condition of the physical evidence taken from the scene of the crime. To protect the crime scene, the officers must accurately establish two boundaries: the centre and the perimeter. – The centre of the crime scene is the area in which the offence was actually committed. – The perimeter consists of the surrounding areas where the offender may have been present or may have left evidence. These areas include any entry or escape routes used by the offender.

 Crime scenes are preserved for three reasons: – to allow for a thorough search of the scene – to seize and collect physical evidence – to ensure physical evidence seized is admissible in court.



Protecting/Preserving the Crime Scene

if evidence is not handled properly it may become contaminated and be inadmissible in court.

 Contamination is the loss, destruction, or alteration of physical evidence. This type of evidence is not admissible in court and may lead police to draw inaccurate conclusions.

 Investigators keep a police log, a written record of what each officer has witnessed at a crime scene or has learned from questioning witnesses or suspects.  Officers use their logs to document their daily activities. Later, these logs will help officers recall events, particularly when they are called to testify at a trial. Investigators also use photographs, sketches, and other recording techniques to document the evidence found at a crime scene.

Officers at a Crime Scene

 Four types of officers investigate a crime scene and each has a separate and well-defined role to play.

1.

Patrol Officer – usually the first on the scene. Primary duty is to secure scene and ensure no evidence is tampered with or lost. Usually puts up yellow tape around the perimeter and conducts initial interviews with witness at the scene. They also arrest suspects if the crime is in progress.

2.

“Scenes of Crime” Officer – Trained in evidence collection/preservation. Usually take photographs, lift fingerprints and foot/tire impressions. They also collect blood/hair evidence. These officers usually work on less serious offences such as break and enter and car thefts.

Officers at a Crime Scene

3.

“Criminal Identification” Officer – Responsible for searching the crime scene, examining scene for evidence, gathering/analyzing evidence and sending certain types of evidence to laboratories for analysis.

4.

“Criminal Investigation Bureau” Officer – Plainclothes detective with experience in a particular area of crime such as homicide, robbery or sexual offences. These officers are trained to supervise the investigation, interview witnesses, interrogate suspects, and draw conclusions from physical evidence and arrest suspects.