1. Chapter 4 Physical Evidence

2. © 2009 McGraw-Hill Higher Education. All rights reserved. LEARNING OBJECTIVES Distinguish between class and individual characteristics. Outline procedures for locating and handling soil and pollen evidence. Understand processes for preserving footwear and tire prints and impressions. Summarize techniques for collecting glass and paint evidence. Discuss methods of collecting and storing fibers, cloth fragments, and impressions. Understand how to locate, identify, and use tools to obtain fingerprints. Describe the importance of forensic dentistry and odontology. Discuss the identification and analysis of bloodstains and spatters. Identify the determinations that can be made from firearm evidence. Outline techniques for identifying questioned documents.

3. © 2009 McGraw-Hill Higher Education. All rights reserved. CLASS AND INDIVIDUAL CHARACTERISTIC EVIDENCE Class: a group of objects or persons with characteristic physical evidence common to it –Examples include soil and hair Individual characteristics can be identified as having originated with a particular person or source –Establishes individuality –Examples include fingerprints and footprints

4. © 2009 McGraw-Hill Higher Education. All rights reserved. CLASS AND INDIVIDUAL CHARACTERISTIC EVIDENCE

5. © 2009 McGraw-Hill Higher Education. All rights reserved. LOCATING AND HANDLING SOIL EVIDENCE Soil evidence is important when the suspect drives/walks on unpaved areas It is picked up by: –tire treads –shoe bottoms –pants cuffs It may also be located in: –subject's vehicle –articles in a suspect's trunk

6. © 2009 McGraw-Hill Higher Education. All rights reserved. PRESERVING FOOTWEAR AND TIRE PRINTS AND IMPRESSIONS Footwear prints and impressions should be photographed: –As part of the general scene –Also photograph with a scale Dental Stone is used in casting impressions

7. © 2009 McGraw-Hill Higher Education. All rights reserved. FOOTWEAR IMPRESSIONS Photographs of footwear impressions at a crime scene –Take general crime scene photos showing the location of the footwear prints. –Take photos from directly overhead using lighting and a tripod. –Include a linear scale next to, and on the same plane as, the footwear prints. –Place a label in the area being photographed to correlate photos with crime scene and photo log records.

8. © 2009 McGraw-Hill Higher Education. All rights reserved. FOOTWEAR IMPRESSIONS

9. © 2009 McGraw-Hill Higher Education. All rights reserved. COLLECTING GLASS AND PAINT EVIDENCE Paint may be collected from the suspect's tools or clothing. Paint can often be collected in dried chips. Glass is a common form of evidence at burglary scenes. Before any glass fragments are removed from a glass window it should be photographed.

10. © 2009 McGraw-Hill Higher Education. All rights reserved. LAMP FILAMENT ANALYSIS An important question often associated with motor vehicle accidents and hit-and-run cases involves whether or not the lights of a suspect vehicle were actually on, or energized. This is particularly important when the suspect vehicle has been crashed or wrecked. Advanced in lamp filament technology now allow the investigator to determine this question.

11. © 2009 McGraw-Hill Higher Education. All rights reserved. COLLECTING AND STORING FIBERS, CLOTH FRAGMENTS, & IMPRESSIONS Fibers are of greater value as evidence than are rootless hairs. Fibers may be located on the body of the victim and/or the suspect. Cloth fragments may be found at the scene of a violent crime. Cloth fragments may also be found at the suspect's point of approach or exit.

12. © 2009 McGraw-Hill Higher Education. All rights reserved. THREE BROAD CATEGORIES OF LATENT FINGERPRINTS Plastic prints –Created when the fingers touch against some material such as putty Contaminated/visible prints –Formed when the fingers are contaminated with such things as ink or blood and touch a clean surface Latent/invisible prints –Left on a surface from the small amounts of body oil and perspiration that are normally found on friction ridges

13. © 2009 McGraw-Hill Higher Education. All rights reserved. MAJOR FINGERPRINT PATTERNS

14. © 2009 McGraw-Hill Higher Education. All rights reserved. CONDITIONS AFFECTING THE QUALITY OF LATENT FINGERPRINTS The surface on which the print is deposited The nature of the material contaminating the fingerprint Any physical or occupational defects of the person making the print How the object on which the prints appear was handled The amount of the contamination

15. © 2009 McGraw-Hill Higher Education. All rights reserved. METHODS OF DEVELOPING LATENT PRINTS Traditional powders Fluorescent Powders Chemicals Cyanoacrylate of superglue fuming Visualization under: –Laser –Alternative light –Ultraviolet illumination

16. © 2009 McGraw-Hill Higher Education. All rights reserved. RUVIS (Reflected Ultraviolet Imaging System) Generic name for a class of lighting and imaging systems that have been increasingly used in the past several years. When the UV light strikes an undetected fingerprint on most nonporous surfaces, it is “bounced” back to he RUVIS and the image is intensified. Prints located in this manner can then be developed and photographed.

17. © 2009 McGraw-Hill Higher Education. All rights reserved. LOCATING PRINTS Crime Scene Technician –This technician is using powder to develop latent prints –Technicians often wear protective equipment –Several points can be seen (Courtesy Nassau County, New York, Police Department)

18. © 2009 McGraw-Hill Higher Education. All rights reserved. PORTABLE SUPERGLUE FUMING CHAMBER Easy to use Produces remarkable results Low cost

19. © 2009 McGraw-Hill Higher Education. All rights reserved. FORENSIC DENTISTRY Forensic odontology is a specialty that relates dental evidence to investigation Analyses of bite marks had played a major role in many cases Teeth marks may be left in food, pencils or other items left at crime scenes Bite marks can help eliminate or identify suspects

20. © 2009 McGraw-Hill Higher Education. All rights reserved. Dental records are very useful in helping to identify unknown persons who have been the victim of fowl play or who have been reported simply missing. (Courtesy Dr. Richard R. Souviron, D.D.S., ABFO, Chief Forensic Odontologist, Dade County Medical Examiner Department, Miami, Florida) DENTAL COMPARISON

21. © 2009 McGraw-Hill Higher Education. All rights reserved. IDENTIFYING AND ANALYZING BLOOD STAINS If blood at the crime scene is fresh and relatively uncontaminated, identification is not difficult If the conditions at a crime scene are otherwise it is more difficult to identify One preliminary field test involves the use of Hemident Blood analyses is important because of the value of DNA typing

22. © 2009 McGraw-Hill Higher Education. All rights reserved. HEMIDENT The use of Hemident in a presumptive or preliminary field test for blood.

23. © 2009 McGraw-Hill Higher Education. All rights reserved. SOURCES OF DNA EVIDENCE These are common sources of blood and DNA evidence that investigators need to be aware of in conducting crime scene searches.

24. © 2009 McGraw-Hill Higher Education. All rights reserved. Firearm Evidence Determination from firearms evidence lab examinations of firearm evidence may answer the following questions –Was this bullet fired from this weapon? –What else can be learned from the bullet? –What determinations can be made from cartridge cases? –What miscellaneous determinations can be made by examination of firearms evidence?

25. © 2009 McGraw-Hill Higher Education. All rights reserved. BULLET IDENTIFICATION When a bullet passes through the barrel of a weapon distinctive scratches are caused These scratches can be compared to bullets fired through firearms in question Identification is affected by the condition of the gun and of the bullets

26. © 2009 McGraw-Hill Higher Education. All rights reserved. (Courtesy Immigration and Naturalization Service, Forensic Documents Laboratory.) COUNTERFEIT SOCIAL SECURITY CARDS Social security numbers are an important source of identification in America Criminals often try to produce social security cards in order to assume new identities Illegal aliens also often try to obtain fake social security cards

27. © 2009 McGraw-Hill Higher Education. All rights reserved. TECHNIQUES FOR IDENTIFYING QUESTIONED DOCUMENTS Handwriting and handprinting examinations There are three types of forgery: –Traced forgery –Simulated forgery –Freehand forgery

28. © 2009 McGraw-Hill Higher Education. All rights reserved. TECHNIQUES FOR IDENTIFYING QUESTIONED DOCUMENTS continued Photocopier examination Paper examination Age of documents Burned or charred paper Altered or obliterated writing Writing instruments mechanical-impression instruments Typewriting