Impressions Teeth Shoe Tire and Tool Marks Classifying

Impressions Teeth, Shoe, Tire, and Tool Marks

Classifying Characteristics • Class Characteristics- Evidence associated only with a common source w Examples- type of gun (handgun vs. rifle), brand of shoe (Nike vs. Adidas), manufacturer of a tool (Craftsman vs. Mac) • Individual Characteristics- Evidence that can connect a crime scene sample to a standard reference sample w Examples- striation marks, wear and tear, chips or gauges

Teeth Marks • Used in homicide and rape cases • Dental records are used to identify remains • Almost everyone has a dental record, unlike fingerprint records

Types of Teeth Incisor w Rip and tear Cuspid/Canine w Tearing Bicuspids/Premolars w Grinding Molars w Grinding and Crushing w Third Molars are Wisdom Teeth

Baby Teeth • Temporary (Deciduous) teeth • Also called Milk teeth • Only 20 teeth • Fall out or dissolve as permanent teeth move into place

Adult Teeth • Average human has 32 adult teeth • Teeth are numbered from lower left (1) to upper right (32) • Orientation and position of teeth make teeth unique • Dental work will help to make teeth unique

Case Studies-Dental Records • Airplane crash: dental records used to identify victims • Oklahoma Bombing: 25% of dead identified by teeth • Jeffery Dahmer: eleven of his seventeen victims were identified by dental remains

Case Studies-Bite Marks • Ted Bundy- Was convicted of several murders in Florida because of his tendency to bite his victim. This was the only evidence that could place him at the scene of the crime.

Footprints and Tire prints • Two types of impressions w Indentations: made in soft material - wet dirt, clay, snow w Residue: from surface of object - blood or dirt • Chemicals can be added to footprint evidence to develop footprints made in blood

Preservation of Impression • Original is best • Photograph all impressions in case of damage • Handprint (sticky material) or Pathfinder (electrostatic) used to lift residue impressions • Casting used for indentations

Analysis of Impression • Similar to fingerprint evidence in collection and analysis • Not based on identifying the brand name but rather matching imperfections from the suspects item to the print from the scene • There are data bases for tire and shoe prints to identify name brands or manufacturers

Examples

Tool Marks • Any impression, cut, gouge or abrasion caused by a tool coming into contact with another object • Usually found at a burglary scene • Wear and use produce discernable nicks and breaks that can be specifically identified

Collection of Tool Marks • Difficult to reproduce a tool mark in the lab • Examination would require several tests of the tool at different angles and pressures • If removal is impossible photos and cast should be used

Analysis of Tool Marks • An examiner should never try to fit the tool back into the tool mark this will alter the evidence • Trace evidence may also be present on the tool or in the tool mark blood, paint, etc.