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Pre-Trial Procedures

Pre-Trial Procedures. Investigating the Crime Scene. DUE PROCESS. A balance must be struck between an individual’s rights and the need for police and courts to have the authority to enforce the law and protect society.

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Pre-Trial Procedures

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  1. Pre-Trial Procedures Investigating the Crime Scene

  2. DUE PROCESS • A balance must be struck between an individual’s rights and the need for police and courts to have the authority to enforce the law and protect society. • Criminal procedure is outlined in the Criminal Code and the Canadian Charter of Rights and Freedoms. • These procedures must be adhered to by both the police during their investigation of a crime, and the prosecutor. • This is called DUE PROCESS.

  3. ONCE A CRIME HAS BEEN COMMITTED, THEN WHAT? • The location where a crime takes place is called a CRIME SCENE; • On arriving at the crime scene, police officers have 3 tasks to perform: • Call an ambulance and assist the injured at the scene. • Call in reinforcements. • Search the crime scene even if witnesses have indicated that the suspects have left.

  4. Protecting and Preserving the Crime Scene (Securing the Scene)

  5. PROTECTING AND PRESERVING THE CRIME SCENE • Police officers need to preserve and protect the crime scene from accidental or intentional contamination by anyone. • Crime scenes are preserved for 3 reasons: • To allow for a thorough search of the scene; • To seize and collect physical evidence; • To ensure that the physical evidence seized is not contaminated. • CONTAMINATION – is the loss, destruction, or alteration of physical evidence found at the crime scene. • If evidence becomes contaminated, it may be deemed inadmissible in court.

  6. EVIDENCE AT THE CRIME SCENE • Crime scene investigation is carried out by officers who are trained in the analysis of physical evidence. They must: • Prepare a description of what they find; • Photograph the scene; • Prepare diagrams or sketches; • Collect evidence • Once the crime scene has been secured, the focus of the investigation is the collection of physical evidence; • When the evidence is brought back to the lab for analysis, it is examined by FORENSIC SCIENTISTS.

  7. WHAT IS FORENSIC SCIENCE? • FORENSIC SCIENCE is the use of biochemical and other scientific techniques to analyze evidence in a criminal investigation • Forensic scientists include: • Pathologists (medical doctors who perform autopsies to determine time and cause of death) • Entomologists (those who study insects); • Firearms specialists; • Chemists • anthropologists

  8. EVIDENCE FOUND AT THE CRIME SCENE – Direct vs. Circumstantial • Direct Evidence • Directly links the accused to the crime • Very hard to dispute • Video evidence, DNA evidence, some witness testimony • Circumstantial Evidence • Indirectly links the accused to the crime; • Gives an idea about what MIGHT have happened • For example, fibres, paint chips, some witness testimony

  9. Physical Evidence • Physical evidence is the type of evidence collected at the crime scene. It includes: • Any object, impression, or body element that can be used to prove or disprove facts relating to an offence; • Physical evidence includes things left at the scene of the crime, such as a knife, fingerprints, gunshot residue, blood, and DNA evidence; • It often carries greater weight in court than evidence obtained through witness statements.

  10. PHYSICAL EVIDENCE - TRACE ELEMENTS • i.e. dirt, dust, and residue, hair and fibres; • Though they may not prove a specific individual committed a crime, trace elements can link a suspect to a crime

  11. TRACE ELEMENTS

  12. Types of Physical Evidence – Body Elements and DNA • Includes blood, semen, mucus, sputum, hair, and skin; • Used to match with the DNA of a suspect; • Blood is the most common; • Hair and fibres are used to compare with those found from a suspect’s belongings; • DNA is different for each person, with the exception of identical twins; • The DNA of every cell in a person’s body is identical, but the pattern is different (except for identical twins): • The DNA profile of a suspect can be compared with the DNA profile found at a crime scene. If they match, they are from the same person; if they don’t, then the investigators need to find another suspect. • DNA is used to either link suspects to a crime with physical evidence, or free them from suspicion.

  13. DNA

  14. BLOOD SPATTER

  15. Blood Splatter Analysis

  16. MORE BLOOD SPATTER...

  17. Types of Physical Evidence that leave Impressions - Tools • Most frequently used are hammers, screwdrivers, and crowbars; • Markings can be analyzed in the lab and matched with wounds found on the victim

  18. Types of Physical Evidence that leave Impressions – Shoe Prints and Tire Tracks • Shoe prints help to determine the height and weight of a suspect, as well as any injuries they might have sustained committing the crime, or whether they were carrying anything, walking, or running. • Tire impression can help determine the type of tires, the make of car, and the direction the car was going

  19. Types of Physical Evidence that leave Impressions - Gloves • Glove impressions can be used to identify a suspect in almost the same way fingerprints are: • The class characteristics (the overall pattern of the glove and the spacing of its stitches) and individual characteristics (worn or torn areas), are compared with the gloves of a suspect.

  20. Types of Physical Evidence that leave Impressions - Fingerprints • The mark left behind by a fingertip; • Prints can be taken from a person’s hands, feet, or toes, but fingerprints are the easiest to work with and classify; • Fingerprint patterns never change and are unique to each individual – no 2 people have the same fingerprint pattern; • Are the best type of impression to use to identify an offender

  21. Fingerprints continued • There are 2 types of fingerprints: • VISIBLE FINGERPRINT – a print that can be observed by the naked eye because it is coated in blood, dirt, grease, or some other substance; • Can be photographed immediately. • LATENT FINGERPRINT – a print that is made by the perspiration and oils that naturally form on the skin surface and cannot be seen by the naked eye; • Must be developed before they can be photographed: • Dusted and then lifted when on non-absorbent surfaces like metal or plastic; • Iodine fuming is used for absorbent surfaces, such as paper and cloth; • A laser beam can be used to illuminate the print – the sweat absorbs the laser and turns the print yellow, allowing it to be photographed.

  22. Types of Fingerprint Patterns • All patterns are one of 3 main types: • Arches – form ridges that run from one side of the print to the other and curve up the middle; • Loops – showing stronger curves than arches with ends that start on one side of the finger, loop around, and end up in the same place; • Whorls – forming complete ovals, often in a spiral pattern around a central point.

  23. Types of Fingerprint Patterns

  24. FINGERPRINT PROCESSING • In Canada, fingerprints taken from a crime scene are sent to a central repository administered by the RCMP in Ottawa; • Identity is determined by comparison – 10 to 12 points must be identical for an expert to form the opinion that the print submitted is that of an individual whose prints are on file.

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