Impression Evidence PDF

Impression Evidence LEC03 – Friday September 13th FRSC2030H Foundations in Forensic Science  LAB01 Has begun Readings posted Course Update TAs & contact info  St. Valentine’s Day Massacre – 1929 Crime during prohibition 7 gang members fo...

Impression Evidence LEC03 – Friday September 13th FRSC2030H Foundations in Forensic Science  LAB01 Has begun Readings posted Course Update TAs & contact info  St. Valentine’s Day Massacre – 1929 Crime during prohibition 7 gang members found executed Goddard examines casings Mob rivalry likely cause December 1929 Fred “Killer” Burke Drunk driving incident Kills Police officer Home gets raided Bullet striation comparison linked weapons to 2 incidents Ted Bundy – 1970 Theodore Robert Cowell 1970s & earlier committing many crimes: Aggravated kidnapping Attempted Murder Burglary Murder His conviction was partly due to bite mark analysis He left a bite mark on the buttocks of one of his victims, it was compared to casts of his teeth Russell Williams – 2010 Former Colonel at CFB Trenton Jan 28th disappearance Tracks left around home Boots & Tires Feb 4th police blockade Tires on his vehicle had very unique tread Officer recognized the unique tread from a tire impression Questioning Footwear & tire tracks Charged with: Murder Forcible Confinement Multiple break & enters  Types of Impression Evidence 1. Fingerprints 2. Tool Marks 3. Bullet Casing Marks 4. Tire Marks 5. Footprints 6. Bite Marks  Evidence Characteristics Class Characteristic Individual Characteristic  Class Characteristics “associated with a group and not a single source” Not unique to one shoe Cannot be used to link unique shoe Made by manufacturers Class examples: Nike symbol Size 11 Pattern (e.g. Ugg) Class Characteristics  Individual Characteristics “a unique common source with an extremely high degree of probability” Unique to each shoe Can be used to link evidence Unique examples: Wear marks Nicks Tears Positive vs Negative Impression Evidence Fingerprints Unique: “no two fingers have identical ridge characteristics” Remains relatively unchanged during an individual’s lifetime Ridge patterns permit them to be systematically classified Lifted by: Powder Chemical Developers Ninhydrin, DFO Tool Marks Imperfections found on the tool can be linked to the marks or impressions they create Firearms Link bullets & casings Lands & grooves Modifications and silencers makes markings more unique Tire Impressions Type of Vehicle Make of car Model of car Direction of travel Speed Swerving Skidding Wear marks Footwear Impressions Shoe size Weight displacement Running Walking Individual shoe Injury Collection Methods 3D Casting Dental stone Sulfur cement SnowStone Snow wax 2D Powders / dust lift Chemical Cyanoacrylate DFO Photography Light shadows / highlighting Bite Mark Evidence Teeth can leave an impression (bruise) Mostly found in assault cases Comparison needed to link a suspect and the evidence: Cast impression Dental x-rays Bite Mark Evidence – NIST 2023 KEY TAKEAWAY #1.1: Forensic bitemark analysis lacks a sufficient scientific foundation because the three key premises of the field are not supported by the data. First, human anterior dental patterns have not been shown to be unique at the individual level. Second, those patterns are not accurately transferred to human skin consistently. Third, it has not been shown that defining characteristics of that pattern can be accurately analyzed to exclude or not exclude individuals as the source of a bitemark. Bite Mark Evidence – NIST 2023 KEY TAKEAWAY #2.1: The entire human dentition is not represented in a bitemark. Bitemark patterns typically only represent the anterior teeth and thus not the full possible dentition of an individual, limiting the amount of information available for an analysis. KEY TAKEAWAY #4.1: There is a lack of research into population frequencies, specific identifying characteristics, and measurements that support the notion that human anterior dental patterns as reflected in bitemarks are unique to individuals. Bite Mark Evidence NIST 2023 KEY TAKEAWAY #4.3: Comparisons between bitemark patterns made on skin, for example multiple bitemarks from the same individual on the same victim, have shown that there exists intra- individual variation in bitemark morphology on the human body such that bitemarks from the same biter may not appear consistent.