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Lecture Notes for First Term

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University of Toronto Mississauga
Forensic Science
Hisham Ragab

Intro • Who’s involved in the process? September 18, 2012 • What is a crime scene? o The scene is simply defined as the actual site of location in which the incident took place o It could be classified in different ways  Primary (scene of the crime) and secondary (dumpsite, where the stolen goods are, all subsequent scenes) CS  Macroscopic and microscopic  Indoor and outdoor • Objectives of CS investigation o To recognize, collect, preserve, interpret and reconstruct all relevant physical evidence at a crime scene o Evidence can be split into 2 areas:  Testimonial evidence: any witnessed accounts of an incident  Physical evidence: refer to any material items that would be present on the crime scene • X o Prove that a crime has been committed o Link a suspect with a scene or a victim o Establish any key elements of a crime o Provide investigative leads o Identify criminal repeated behavior o Establish the identify of a victim or a suspect o Verify verbal witness testimony o Exonerate the innocent o Identification of unknown substances o Reconstruction of the crime. (How not who?) • CS Processing protocol o These basic functions or tasks are as follows:  Recognition or identification of CS  Survey and examination of CS • Walk-through • Note transient or conditional evidence and consider weather conditions • Note points of entry or exit and paths • Record brief initial observations • Consider precautions and equipment needed  Documentation of CS  Collection and preservation of evidence  Interpretation of evidence  Reconstruction of events • CS Management o CS Investigation Models:  Patrol officers and detectives  Specially trained CS civilian technicians  Major CS team  Forensic lab CS scientists  Collaborative team • First Responding Officer o Duties of the FRO: Safety Comes First o Assist the victim (Injured Victim) o Search for and arrest the suspect o Identify witnesses o Secure the CS  Establish scene barriers  Assign a scene security officer  Initiate a written CS security log (contamination) o Report any changes or alterations made to the CS • CS Documentation o Taking notes o Video recording o Photographing the CS o Sketching the CS o Digital imaging at the CS • CS Searches o Line or strip method o Grid method o Zone method o Wheel or ray method (used when you find a piece of evidence) o Spiral method (used when you find a piece of evidence) • Beyond the crime scene o Victim’s clothing o Fingernail scrapings o Head and pubic hairs o Blood o Vaginal, anal, and oral swabs (in sex related crimes) o Recovered bullets from the body o Hang swabs from shooting victims (for gunshot residue analysis) • Physical Evidence o Any material object, introduced in a trial, intended to prove a fact related to the incident o Physical evidence refers to any items that comes from a nonliving origin, while biological evidence always originates from a living being o Types of evidence  Impressions evidence  Forensic biology  Trace evidence  Firearms evidence  Questions documents o Broader view of physical evidence  Anything can be physical evidence, in any state or form o Forms of physical evidence  Transient: temporary in nature – odor, temp, imprints & indentations • Must be collected first because it will go away quickly  Pattern: produced by forcible direct contact – blood spatter, glass fracture, fire burn, tire, powder residue, clothing and body position  Conditional: produced in a certain event or action – light, fire (colour, direction, speed & temp)  Transfer: produced by physical contact b/w persons or b/w persons and objects  Dr. Edmond Locard was a pioneer in forensic science • Basic principle: every contact leaves a trace” o Known as Locard’s exchange principle o Guidelines for evidence collection and packing  Personal Protective Equipment (PPE)  The CS investigator should change gloves and forceps after each item is collected in order to avoid cross contamination o Biological evidence general guidelines  Should be allowed to air dry, be packaged in paper bags, and be stored under lab conditions  Place liquid items in collection tubes & refrigerate  Consider ref samples to be collected from both victim and suspect o Chain of custody  Chain of custody – list of all persons who came into possession of an item of evidence  Continuity of possession, or the chain of custody, must be established whenever evidence is presented in court as an exhibit  Adherence to standard procedures in recording the location of evidence, marking it for identification, and properly completing evidence submission forms for lab analysis is critical to chain of custody  This means that every person who handled or examined the evidence and where it is at all times must be accounted for o Who provides forensic analysis?  Forensic analysis is usually carried out by experts working ind or in teams  Usually they will have a minimum of a four year degree, a forensic biologist will have a B.Sc. in biology, biochem, etc o Role of the forensic scientist  Often includes work in a lab, examining and analyzing evidence with tools and techniques specific to his/her specialty o Expertise  Experts who present and interpret the results of lab tests must be ‘qualified by knowledge, skill, experience, training or education’. o Forensic laboratories  RCMP, OPP, Centre of Forensic Sciences o What is a forensic examiner?  Collects data and interprets said data in an attempt to establish a truth • Function: commonly used in court by both the prosecution and defense to establish the credibility of a person on the witness stand • Significance: the opinion of a forensic examiner in a specific field can often be used in court as admissible evidence • Types: forensic examiners can come from almost any professional field • Opinion of a forensic examiner in a court case can greatly influence the opinion of the jury o Evidence in the legal system  Must prove that the evidence you have is unique to that particular case  Class evidence (class characteristics)  Individualizing evidence o CS reconstruction of interpretation  The reconstruction of cs is a misnomenclature  We are in reality interpreting the info that we find by examining and processing the scene for evidence  You are placing your interpretations in a logical order to reconstruct what has taken place in the cs September 25, 2012 Guest Speaker • Benefits – InvestigativeAid o Type of Shoe / Tire track o Pattern Design o Number of Suspects o Connections to other crime scenes o Sequence of events – directionality o Corroborate versions of events • 2D v 3D Impressions o 2D  Has length and width, but not a significant depth  Something removed, or a deposition • General or “Class” Characteristic o An intentional or unavoidable characteristic that repeats during the manufacturing process and is shared by one or more other shoes or tires o Tread pattern o Type of footwear o Size • Accidental or ‘Individual’Characteristic o When something is randomly added to or taken away from the original structure of the shoe or tire that either causes or contributes to making that shoe or tire unique o Physical shapes o Spatial relations o These provide the uniqueness and individualizing strength • Identification process (Fingerprints vs Footwear) o Fingerprint conclusions  Doesn’t change o Footwear conclusions  More variability  Still in production  Years produced  How long since production ended  How many made o Either identification, exclusion, or can’t be sure • Detection or Enhancement o Light: ambient, white, oblique,ALS, Laser o Fingerprint Powder o Chemistry (blood reagents, Bromophenol blue, Potassium Thiocyanate, Iodine Fuming) Professor • Fingerprints o Impression left by the friction rides of a human finger o Are unchangeable – can destroy fingerprint, but cannot change it • History of Fingerprints o Used as signatures in ancient Babylon in the second millennium BCE o Chinese merchants used fingerprints to authenticate loans o In 1880, Dr Henry Faulds published his first paper  Talking about fps and their legal significance  Can be classified into diff groups o Alphonse Bertillon  Anthropometric system to identify inds in 1879 o Frances Galton 1882  All fps were unique and didn’t change throughout life  Categorized patterns of fingerprints into loops, arches, and whorls  Developed a classification system that allowed for a person’s fingerprints to be placed in a category o Edward Henry  Developed alternate classification system that was adopted in England  System has been modified and is still in use in US and Europe o 1904 – Edward Foster convinced RCMP superiors of utility of fps o Development of FPS  During weeks 10-17 of gestation, ridges are formed on the epidermis  Fps are static and don’t change with age  Pattern changes in size, but not shape, as person grows  Pattern type is inherited from mother & father, but exact arrangements of features are random, not inheritable o FPTypes  Exemplar Prints • Known prints, collected from a subject  Patent Prints • Chance friction ridge impressions which are obvious to the human eye  Plastic Prints • Friction ridge impression left in a material that retains the shape of the ridge detail  Electronic Recording  Latent Fingerprints • Hidden of invisible. Chemical and physical processing techniques permit visualization of invisible latent print residues • Criteria for a successful method o Works on a variety of surfaces o Preserve the integrity of the impression • Methods employed can be divided into: o Physical  Power dusting using the proper brush  Magnetic brush: gentle technique, less damage to latent print ridges o Chemical  Silver nitrate  Iodine fuming  Ninhydrin o Special illumination  Simple oblique lighting  Alternate light  Laser illumination, monochromatic light  Luminescent nano-particles for latent fingerprints enhancement • Bloody fingerprints o May or may not require enhancement o DNAprofiling of the blood by PCR • Recognition, Collection & Preservation of FP Evidence o Recognition: training and experience o Documentation: photography, notes & sketches o Objects should be collected intact and submitted to lab o If collection is impossible latent development techniques at scene • FP Examination o Known as dactyloscopy, or hand print id, is the process of comparing two instances of friction ridge skin impressions o FP id, also referred to as individualization, involves an expert, or an expert computer system October 2, 2012 • FIS Mandate o Examination, photographing and video taping of crime scenes o Examination/collection/comparison of articles for fps and/or physical evidence o Submission of physical evidence to the Centre of FS or other Forensic Experts • Locard’s Principle • Calls for Service o Arson  Deliberate burning of property for malicious or fraudulent purposes o Recovered Stolen Vehicles o Theft fromAuto o Break & Enter (Attempts)  Authority • Can’t enter premises w/o an authorized person present to give consent o Suitable surfaces for FP Examination  Smooth  Hard  Dry  Clean  Sufficient size  Paper (chemical treatments) o Footwear Impressions  Same as last class o Motor Vehicle Collisions o Mischief  Typically involve spray painting or minor damage to property o Industrial accidents o Robbery o Forensic Video Analysis o Death  4 classifications of death • Natural Causes • Accidental • Suicide • Homicide  Presuming death • Never presume death except in cases of: o Decapitation o Transection o Massive head wound o Decomposition o Fingerprint theory: friction ridge skin  Ridges and furrows allow for friction b/w any other surface they contact  Four premises of friction ridge ID • Form in fetal stages, before you’re born. Grow with you, do not change overtime o Unique and random (differential growth) • Persistent throughout life except for permanent scarring/disease • Unique and never repeated. • …  Development time for friction ridge skin • B/w 17-24 weeks o Ridgeology  Human Perception  You see with your MIND through your eyes o Digit determination  When looking to examine an fp, the examiner should attempt to determine how the print was made  This helps reduce the number of known prints searched  Which finger? o Fingerprint Workflow:AFIS Search  AFIS is only a search tool to narrow down ‘possible’candidates o Friction Ridge Identification  Established through the agreement of friction ridge formations, in sequence, having sufficient uniqueness to individualize o Levels of ridge identification  Level 1: Overall ridge flow  Level 2: Ridge path – can identify people at this level • Ending ridge • Dividing ridge or bifurcation  Level 3: Size and shapes of pores and ridges • Pores • End shapes and angles • Edge shapes • Width • The smaller the feature, the more individualizing power it has o ACE-V  Analysis  Comparison  Evaluation  Verification o Three conclusions in Evaluation  Identification  Exclusion  Inconclusive o Abnormal circumstances  Have to assign a value  Amputation  Polydactyly – having more than normal number of fingers or thumbs • Have to ignore digits  Syndactyly • Partial or complete webbing of 2 or more fingers  Dysplasia • Ridge units that did not form completely October 9, 2012 (Dr. Carolan Wood) • Focus on the big picture • 8 topics for this section o 6 questions per chapter o General knowledge questions that are basic to an understanding of particular discipline ForensicAnthropology (FA) o Use knowledge of human skeleton and archaeological techniques to solve problems o Main role: contribute to search plan to search for, recover, and analyze human remains and present them in court o Specifically deal with human remains that are  Skeletonized or  Badly decomposed o Main goal is identification  Allows family members closure; allows people to complete grieving process • Ethics o Legal rights/responsibilities regarding human remains  Governed by a number of acts (don’t need to know names) o If you find a burial, it’s not to be disturbed, no matter what it is • Locating/recovering human remains o What are the resps?  Contribute to a search plan to locate and recover huma
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