Forensic Crime Scene Analysis



CRJ 311: Forensic ScienceLecture 4 - Trace EvidenceIntroduction to Trace EvidenceTrace evidence:Common examples:Introduction to Hair EvidenceHuman Hair:Hair can also determine:James Charles KoppWho was he?What group was a part of?What evidence was collected at the crime scene?Morphology of HairHair: The Hair ShaftThe hair shaft is composed of:Cuticle:Cortex:Medulla:The Hair Shaft “Cuticle”The cuticle is the outer layer covered with scalesWhere do the scales point?Do they differ between species?The three basic patterns are:Hair ShapeHair can be what types of shapes?What is hair important?The RootHair roots may reveal what?Do they look different if they fell out or were pulled out?What shape is an animal root?DNA from HairNuclear DNA:Where is it found?If pulled out, what would be attached?Mitochondrial DNA:Where is it found?Can it be typed?Is it easy and cheap?Collection of Hair EvidenceHair evidence is easy to collect and storeDoes CSI need to collect control hairs?From where and how many?A Case for Hair EvidenceNapoleon died in exile in 1821.What did hair analysis suggest?What did skeptics believe?Modern day forensic analysis allows these types of examination and insights to history.SUMMARY: What Can Hair Tell Us?Can the body area from which a hair originated be determined?Can the racial origin of hair be determined?Can the age and sex of an individual be determined from a hair sample?Is it possible to determine if hair was forcibly removed from the body?Are efforts being made to individualize human hair?Can DNA individualize a human hair?Fiber EvidenceFiber: What types are there?Types of FibersNatural: Artificial:Identification of Fiber EvidenceMicroscopic observationWhat methods do they use?Collection of Fiber EvidenceClothing:Why shouldn’t you put different items on the same surface before bagging?Tape lifts:Removed fibers:Fiber Evidence in CourtUsed in many court cases.Who was Wayne Williams?What was the crucial piece of evidence?Paint Chip EvidenceAutomobile accidents and break-ins mostly.How many paints must a criminalist compare?Auto paints usually consist of what 4 layers:Paint Chip AnalysisLayer structure is most important in analysis.Most paint does not have a layer structure of sufficient complexity to identify a single source.Stereoscopic microscope:Pyrolosis Gas Chromatography:Collection of Paint EvidenceWhere is it collected from?Why are tweezers used?Paint smears:Glass EvidenceGlass:Two TypesTempered:Laminated:Comparing fragments:Glass Fracture EvidenceBullets produce cracks when penetrating glass:Radial:Concentric:Analysis determines direction of impact using 3R Rule:Which Bullet Hole Came First?Cracks radiating out from the hold will stop when they encounter another crack.What do basic principles of physical science allow?Collection of Glass EvidenceShould glass be collected from scenes?Often found where?Should be placed in what?Soil EvidenceSoil is easily transferred to suspects making it valuable evidence.How do soils differentiate?How is a visual comparison made?What do crime labs use?Collection and Preservation of SoilStandard/reference soil samples should be collected at various intervals in a 100 yard radius from the crime scene.Should soil be removed from evidence?What is it wrapped in? ................
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