Theory of Crime Scene Investigation.

Effects of Injury on Skin

  • Injuries to the Dermis Layer:

    • Result in the formation of a scar.

    • The scar is a result of the repair/healing process that creates a unique feature in friction ridge skin.

Scars

  • Uniqueness of Scars:

    • Scars are as unique as normal friction skin.

    • Formed randomly; two or more injuries cannot produce identical scars.

    • Scars are persistent and hold value in comparison due to their uniqueness.

Identification Standards

  • Points for Identification:

    • No valid basis exists for requiring a predetermined minimum number of friction ridge characteristics for positive identification.

    • The International Association for Identification (IAI) stated this on August 1, 1973, and reiterated at a symposium in Ne’urim, Israel, in June 1995.

    • Evett and Williams (1996) discussed the historical basis in relation to the Sixteen Points Fingerprint Standard in England and Wales.

ALS/FLS Defined

  • ALS/FLS:

    • Used for over 40 years to detect and document evidence such as fingerprints, fibers, hair, and bodily fluids.

    • Portable units beneficial for use at crime scenes and in laboratories.

    • Assists in searching for evidence that needs lab confirmation for DNA.

Operation of ALS/FLS

  • Lightwave Emission:

    • Operates between 200-700nm.

    • Barrier filter allows longer fluorescent wavelengths to pass through while blocking shorter wavelengths.

    • Excitation of molecules within substances causes fluorescence, leading to both fluorescent and light wavelengths being refracted off evidence.

ALS Photography Settings

  • Multiple wavelength settings available; adjustments made through trial and error.

  • Required gear:

    • Goggles (orange, red, or yellow) associated with specific wavelength filters.

    • Camera setup includes matching filter color, tripod, and timed exposure.

Historical Context

Alphonse Bertillon (1882)

  • Developed a system based on 11 body measurements.

  • Standardized mug shot taking; system known as Anthropometry was challenging to implement and was eventually replaced by fingerprinting.

Bertillon's Photography Method

  • Introduced high tripod-mounted cameras for photographing crime scenes without disturbance, incorporating scales in photos for reference.

Hans Gross (1891)

  • Published "Criminal Investigation," the first comprehensive guide about using physical evidence to solve crimes.

  • Coined the term “criminalistics.”

Edmund Locard (1910)

  • Established the first crime laboratory in Lyon, France.

  • Introduced Locard’s Exchange Principle: “It is impossible for a criminal to act, without leaving traces of their presence.”

General Historical Developments

  • 1924: First U.S. crime lab opened in Los Angeles.

  • 1950: Establishment of the American Academy of Forensic Sciences (AAFS) in Chicago and publication of Journal of Forensic Science.

  • 1960: Lucas described gas chromatography's applications in forensic labs for petroleum products.

  • 1974: Detection of gunshot residue (GSR) technology developed.

  • 1977: Gun fingerprinting method using cyanoacrylate fuming discovered in Japan.

  • 1986: First use of DNA evidence in a crime case in England leading to a murder conviction.

  • 1996: FBI began using computerized AFIS fingerprint database.

Recent Developments

  • 2009: NAS report highlighted deficiencies in forensic practices.

  • 2012: Hart House Report published on forensic science in Canada.

  • 2016: PCAST Report discussed comparison disciplines in forensic science.

Crime Scene Processing Overview

Initiation

  • Triggered by a call/request.

  • Consideration of the lawful authority to access scenes and avoid contamination (PPE).

Authority in Crime Scene Investigation

  • Must have proper authority through:

    • Consent (voluntary)

    • Search warrant (Criminal Code, Controlled Drug & Substances Act)

    • Legislation (e.g., Coroners Act)

Roles in Crime Scene Investigation

  1. Learn: Gather information and intelligence.

  2. Plan: Conduct a scene walk-through.

  3. Act: Execute processing actions.

Step 1 - Learn Information/Intelligence

  • Engage with first responders.

  • Assess safety concerns and required PPE.

  • Determine need for search consent/warrant or legislation for authority.

    • Create a common path for authorized entry/exit.

    • Establish boundaries and prioritize scene based on size/nature of evidence.

Step 2 - Plan (Scene Walk Through)

  • Conduct initial inspection to identify fragile evidence.

  • Formulate a processing plan by prioritizing initial tasks.

    • Assign roles among team members for collection and documentation.

    • Develop a hypothesis regarding the scene.

Step 3 - Act - Processing the Scene

  • Typical order of operations includes:

    1. Photography

    2. Video (if needed)

    3. Notes

    4. Rough sketch with measurements

    5. Scene examination (alternate light source analysis, pattern analysis)

    6. Exhibit collection after photography

    7. Search for additional evidence

Photography Technique

  • Begin with exterior shots and progress inside (general to specific).

  • Incorporate types of photographs such as aerial views when necessary.

UAV (Unmanned Aerial Vehicle)

  • Cost-effective for police deployment.

  • Provides fast access and meets court-quality standards in image production.

Video Documentation

  • Utilized for a comprehensive overview of larger crime scenes.

  • Starts outside, moving in, avoiding audio narration, generally not applied to smaller scenes due to potential lack of value.

Specialists in Scene Processing

  • Include roles such as drone operators, dive team members, forensic specialists, search teams, and coroners.

Lawful Authority and Consent

Importance of Lawful Authority

  • Crime scenes need lawful access for processing and exhibit seizure, which can only be obtained through informed consent, search warrants, or legislation.

Consent

  • Voluntary consent allows police to examine premises (residences, vehicles, businesses) without legal proceedings.

    • Example: A business reporting a break-in grants police access to the scene.

  • Case Reference: R. v. Wills (1992) outlined necessary conditions for informed consent.

Conditions of Informed Consent

  1. Individual consented to the search.

  2. Individual must have authority to consent.

  3. Individual was aware of the intended police actions.

  4. Consent was given voluntarily (no threats).

  5. Individual was informed of their right to refuse consent.

  6. Individual understood potential consequences of consent.

Search Warrant - Section 487 Criminal Code

  • Authorizes police to search a location with reasonable grounds for a limited time.

  • Important: Search warrants for controlled substances require separate authorization under the Controlled Drugs and Substances Act (CDSA).

Case Studies on Lawful Authority

Case Study 1: High-profile Incident

  • Incident regarding the property manager near York University with unlawful conduct.

  • Police error in obtaining a search warrant led to legal challenges that pointed to police negligence.

Case Study 2: Criminal Negligence

  • Scenario where two individuals' struggle over a shotgun resulted in injury.

  • Police obtained a search warrant for the residence to find relevant evidence, including the shotgun and ammunition.

  • Discovery of illegal drugs inside the location required a separate search warrant due to CDSA.

Evidence Types

  • Impression Evidence:

    • Fingerprints, footwear, tire tracks.

  • DNA Evidence:

    • Blood, hair, bodily fluids.

  • Physical Evidence:

    • Clothing, weapons, tools, documents.

  • Digital Evidence:

    • Computers, security camera footage, mobile phones.

DNA Evidence Collection

  • Follow a systematic approach in photographing evidence types such as blood evidence with overall, mid-range, and close-up shots.

DNA Evidence Pathway

  • Focus on procedures for recording, collecting, and submitting DNA evidence.

  • Ontario guidelines for collection procedures.

Centre of Forensic Sciences (CFS)

  • Established in 1932, the second lab in Canada, independent of law enforcement.

  • Sections:

    • Biology, Chemistry, Document Analysis, Firearms, Toxicology.

  • Must pre-approve submissions and follow the Handbook of Forensic Evidence guidelines.

DNA Sections within CFS

  • High Volume Service (HVS):

    • Focuses on property crimes; accepts specific swabs.

  • Violent Crime Service (VCS):

    • Handles serious offences such as homicides and sexual assault.

DNA Designated Offences

  • Primary Offences:

    • Mandatory DNA submission requirements for adults and youth.

  • Secondary Offences:

    • Offences that can lead to imprisonment for five years or more.

DNA Swab Classification for Submission

  1. Swabs of suspected blood (BLS)

  2. Drink container swabs (DCS)

  3. Partially eaten food/utensil swabs (FDS)

  4. Saliva contact swabs (SAS)

  5. Weapon swabs (WPS)

  6. Airbag swabs (ABS)

  7. Other swabs (OTH)

Swabbing Techniques

  • Blood Swabbing:

    • Avoid over-saturation, use a dry swab for wet stains, and a moistened one for dried stains.

  • Drink Containers:

    • Swab containers used for the relevant timeframe with a moistened approach.

  • Utensils/Food:

    • Collect items used within the time frame, using a moistened swab.

  • Saliva and Weapons Swabs:

    • Collect evidence from contact items carefully; weapons bring their own conditions for swabbing.

DNA Profiles and Databases

Canada – National DNA Data Bank (NDDB)

  • Established in 2000, supports crime investigations by linking crimes via DNA analysis.

  • Operates with two indices:

    • Convicted Offender Index (COI): Profiles of offenders.

    • Crime Scene Index (CSI): Profiles from crime scenes.

USA – FBI Codis

  • CODIS System: Allows for DNA exchange between various labs.

United Kingdom – National DNA Database

  • World’s first national database with over 4 million profiles, including arrests versus charges data.

Interpol DNA Database

  • Contains profiles from various member nations; assists in investigating missing persons and unidentified remains.

Summary

  • Understanding your lawful authorities is crucial.

  • Approach your work methodically; always consider scenarios ahead of time.

  • Continually assess the scene’s situation; be prepared for unexpected developments.

References

CFS (2021) Retrieved from:

  • https://www.mcscs.jus.gov.on.ca/english/centreforensic/CFSintro.html