Physical Evidence bsapp com Types of Analysis n
Physical Evidence bsapp. com
Types of Analysis n. Comparison n. Visual n. Microscopic n. Chemical bsapp. com
Comparison bsapp. com Most types of evidence require a control with which to be compared
Visual Analysis Evidence utilized through unaided observation bsapp. com
Microscopic Analysis Evidence observed with the use of some type of microscope bsapp. com
Chemical Analysis Evidence subjected to any type of chemical procedure bsapp. com
Review…. n Name the four types of analysis of evidence and give two examples of each.
Types of Evidence bsapp. com
Documents n. Hand written n. Type or Printed n. Authenticity? bsapp. com
You will see two sets of handwriting samples from the same 10 people. See if you can match each sample in the column ‘A’ with its correct mate in column ‘B’. n CSI: THE EXPERIENCE — Web Adventures
n. How Glass broken? (Small hole? Big pieces? Inside or outside? ) n. Link a suspect to a crime scene n. Any fingerprints? n. Any blood? bsapp. com
Soils, Minerals, Wood, and Other Vegetative Matter. n. Location n. Link suspect n. Trace Evidence bsapp. com
Fingerprints n. Mainstay of Forensics n. Who is on file? bsapp. com
Hair n. What type? n. How removed? n. Match to a person n. DNA bsapp. com
Fibers n. Link suspect to a location or victim n. Origin? bsapp. com
Firearms and Ammunition n. Circumstances of discharge n. Link to suspect n. Link to weapon n. Link to victim bsapp. com
Powder Residue n. GSR Test n. Evidence of shooting n. Circumstances of shooting n. Type of weapon bsapp. com
Tool Marks n. Match tool to scars bsapp. com
Explosives & Propellants n. Link to suspect or victim n. Origin bsapp. com
Impressions bsapp. com
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Drugs n. Type of Drug? n. Strength? n. Origin? n. Legal? bsapp. com
Paint n. Origin n. Match bsapp. com
Blood, Semen, Saliva, Organs, & other Physiological Fluids n. Origin n. DNA n. Condition bsapp. com
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1. What are the four types of analysis? 2. Explain what “tool marks” are and how they are used in CSI.
What does a CSI observe with each of the following evidences? 1. Documents 2. Broken glass 3. Vegetative & soil samples 4. Hair 5. Fiber 6. Firearms and ammunition 7. Powder residue 8. Impressions 9. Drug samples 10. Body fluid
Glass Fractures bsapp. com
►A burglar shatters a window. Later, police discover glass fragments embedded in his shoes and jacket. A shooter fires bullets through a window but claims someone inside shot at him first. Cracked, fractured or shattered glass yields crucial clues for investigations of crimes and accidents. Forensic glass analysis uncovers those clues using a variety of scientific processes. ► Forensic analysis of glass fractures reveals clues about projectiles, weapons and direction of force.
►How Glass broken? ►Link a suspect to a crime scene ►Fingerprints ►Blood bsapp. com
► Radial cracks look like spokes in a bicycle tire, while concentric cracks resemble ripples in a pond. Add gunpowder residue, and there is no doubt someone fired a gun.
Fractures Radial Concentric bsapp. com
►Glass Direction of Penetration bends in response to a force exerted on its surface. When the limit of its elasticity is reached the glass will fracture. ►A projectile hole is inevitably wider at the exit side. ►Often difficult to determine the size and shape of hole in glass whether it was made by bullet or by some other projectile. bsapp. com
Stress Marks A projectile hole is inevitably wider at the exit side, and hence its examination is an important factor when determining the direction of impact. bsapp. com
Direction of Penetration Radial Concentric bsapp. com
Radials • • • Produced first Form on side of glass OPPOSITE to where impact originated. Like spider webs that spread outward from the impact hole bsapp. com
Concentric • Form SECOND • Encircle the projectile hole • Start on the same side as that of the force. bsapp. com
Successive Penetrations A fracture always terminates at an existing line of fracture bsapp. com
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Glass fragments from a crime or accident scene sometimes stick to weapons, tools, automobiles or clothing. Forensic glass examiners compare the density of glass fragments-typically, one sample from a suspect and one from the scene of the accident or crime. If the densities fail to match, police may have enough information to exclude fragments as coming from the crime scene source. ► However, identical densities do not indicate a match, since many types and samples of glass may share the same density. Therefore, forensic glass examiners also analyze the refractive index of both samples. Refractive index measures the ratio of the velocity of light as it passes through a medium versus through a vacuum. A match in refractive index may mean that two glass samples came from the same source, although no glass expert can proclaim that with 100 percent certainty. ►
Review ► Name the four types of c. s. i. analysis. ► Give three examples of each type of analysis ► Name 12 types of evidence. ► Explain how each evidence would be used. ► Example tool marks and their use in forensics. ► Draw example of radial and concentric cracks in glass. ► Explain how to tell successive penetrations (eg. which came first) ► Name two other methods used to analyze glass fragments.
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