1. Forensic science The application of science to those criminal and civil laws that are enforced by police agencies in a criminal justice system.

3. Physical Evidence Any and all objects that can establish that a crime has been committed or can provide a link between a crime and its victim or a crime and its perpetrator

4. Classification of Physical Evidence Trace evidence Direct evidence Prima facie evidence Circumstantial evidence Exculpatory evidence  extremely small items  eyewitness testimony  aka Direct Evidence  implies a fact and is used to incriminate a person  helps to prove that an accused individual is not guilty

5. Another commonly used classification of physical evidence Corpus delicti Associative evidence  establishes that a crime has been committed  links suspect with the crime.

6. Physical evidence utilization in other areas of forensic investigation Provides investigative leads for a case Ties one crime to a similar crime or connects one suspect with another Corroborates statements from witnesses to or victims of a crime

7. The elements of a crime help to determine what will be useful as evidence. Besides knowing what types of evidence to search for, it is necessary to know where evidence is most likely to be found. Besides knowing what types of evidence to search for, it is necessary to know where evidence is most likely to be found.

9. Types of physical evidence Blood ÙConventional serology: ò presence of blood in stains ò species identification and ABO grouping ÙDNA analysis can associate victim and/or suspect with each other or with the crime scene BLOODSTAIN PATTERNS ò How high and fast did the blood fall SEM: erythrocytes & lymphocytes

10. Types of physical evidence BODY TISSUES Ù organ samples collected at autopsy, including blood, urine and stomach contents DRUGS & CONTROLLED SUBSTANCES Ù plant materials, powders, tablets, capsules òToxicological analysis ò volatile compounds (ethanol, methanol, isopropanol) ò heavy metals (arsenic) ò nonvolatile organic compounds (drugs of abuse, pharmaceuticals) ò poisons (strychnine, cyanide) òTrace drug presence, identity, and quantity Black tar heroine wrapped in cellophane

11. Types of physical evidence DOCUMENTS Ù paper and ink analysis Ù handwriting comparison to determine authenticity òtyped, handwritten and printed materials for evidence of forgery òindented writings, obliterated or altered writings, used carbon paper, burned or charred paper Obliterated writing examination

12. Types of physical evidence HAIRS Ù hairs analysis can determine Ù Morphological features Ù DNA analysis Ù Toxicological examination  FIBERS òHuman/animal òRace òBody area òCosmetic treatments òMethod of removal (crushed, cut, burned, forcibly removed, fallen out naturally) òStructural differences in peoples’ hair òPositive identification òPresence of drugs and poisons òType òColor, composition construction

13. Types of physical evidence Two hairs being examined under a comparison microscope Flax fibers viewed with polarized light

14. Types of physical evidence FINGERPRINTS òRidge characteristics are one of the strongest pieces of evidence to identify a person FIRE DEBRIS & EXPLOSIVES RESIDUE EXAMINATIONS òidentification of accelerants and explosive residues 23 matching characteristics Unburned accelerator liquid on a soot covered carpet

15. Types of physical evidence FIREARMS & AMMUNITION Ùindividual microscopic marks ò identification, source, operability of firearms. Ùdetection and characterization of gunpowder residues Ùmuzzle-to-garments distance estimation GLASS FRAGMENTS ò Cause of breakage ò Direction of breakage force ò Physical fitting ò Glass fragment comparisons Photomicrograph: test bullet - questioned bullet Glass fracture produced by a high-speed projectile

16. Types of physical evidence PAINT & PAINT PRODUCTS Ùanalysis and comparison of paint transferred from the surface of an object to another during the commission of a crime: òSuspect vehicle impacting a victim vehicle; a pedestrian or a stationary object òTool impacting stationary object ÙPaint databases can help identify the year, make and/or color of a motor vehicle from a chip of paint left at the scene. Paint Layers on Wood Surface

17. Types of physical evidence TOOLMARK IDENTIFICATION òmicroscopic side-by-side comparison òattempts to link a particular tool with a particular mark to the exclusion of any other tool ROPE & CORDAGE òcomposition, construction, color and diameter Spacing between teeth in gripping -major role in toolmark examinations òManufacturer

18. Types of physical evidence SOILS & MINERALS òcomparison between two or more soils to determine if they share a common origin òcolor, texture, composition comparison WOOD side or end matching, fracture matching and species identification. Cross-section - Xylem Layers of soil exposed at a grave site. Each layer must be sampled

19. Types of physical evidence OILS/GREASE & COSMETIC PRODUCTS SHOEPRINTS & TIRE TREAD IMPRESSIONS òhòhòhòhave value for forensic comparisons. òcòcòcòcan provide positive identification of the suspect’s shoes or tires from the suspect’s vehicle. òpossess unique composition for comparison Shoeprint collected using a gelatin lifter.

20. Characteristics of evidence Class characteristics Individual characteristics  Features, that place an item into a specific category  features that distinguish one item from another of the same type

21. Class Characteristics of Blood Can apply the product rule to narrow the focus. What percentage is O+? 36.6% What percentage has all of these blood factors? 0.004%

22. Class Characteristics Examples: new factory painted cars with only two-layers of paint Uses of Class Characteristics are usually to corroborate the events with data that are free of human bias

23. Individual Characteristics Examples: DNA, fingerprint ridges, grooves/striations on a bullet or toolmark, irregular and random wear patterns on tire or shoe impressions, handwriting characteristics, fitting together pieces of broken objects, matching the striations in sequentially made plastic bags, etc. Ex. the probability of two people having the same fingerprints is 1 / 10 60

24. Individual Characteristics

26. Individual vs. Class Characteristics

27. The more objects that can place a suspect at the scene, the higher the probability that the person was there, even if only class characteristics are present. Individual and Class Characteristics can often exonerate a person as well.

28. Processing physical evidence discovering, recognizing and examining it; collecting, recording and identifying it; packaging, conveying and storing it; exhibiting it in court; disposing of it when the case is closed.

29. RAGE!!