Physical Evidence Chapter 4

LEARNING OBJECTIVES Distinguish between class and individual characteristics. Contrast known and questioned sources. Describe the basics of taking soil samples. Explain how to cast a shoe impression using Dental Stone. Summarize the proper way to collect loose paint chips at a crime scene. Differentiate between radial and concentric fractures. Explain minutiae. Describe how plastic prints are formed. Summarize dusting for latent prints using traditional powder. © 2012 McGraw-Hill Higher Education. All rights reserved.

LEARNING OBJECTIVES Identify five circumstances in which forensic odontology can be an asset. What conclusions are possible from the examination of hair? Define “touch DNA.” Explain how to locate “hidden blood” at a crime scene. Describe how to process a revolver found near a body at a crime scene. Discuss how to collect a tool impression in a doorframe where a prying-type action was used to gain entry. Define questioned document. © 2012 McGraw-Hill Higher Education. All rights reserved.

Class Versus Individual Characteristics 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 © 2012 McGraw-Hill Higher Education. All rights reserved.

Comparison Samples Unknown or questioned samples Recovered crime scene sample whose source is questioned Questioned evidence that may have been transferred to an offender during the commission of a crime and been taken away by him/her Evidence from an unknown or questioned source that can be used to link multiple offenses © 2012 McGraw-Hill Higher Education. All rights reserved.

Comparison Samples Known samples Standard or reference sample Control or blank sample Elimination sample © 2012 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 © 2012 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 © 2012 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. © 2012 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. © 2012 McGraw-Hill Higher Education. All rights reserved.

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. © 2012 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 © 2012 McGraw-Hill Higher Education. All rights reserved.

Major Fingerprint Patterns © 2012 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 © 2012 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 © 2012 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. © 2012 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 © 2012 McGraw-Hill Higher Education. All rights reserved. (Courtesy Nassau County, New York, Police Department)

Portable Superglue Fuming Chamber Easy to use Produces remarkable results Low cost © 2012 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 © 2012 McGraw-Hill Higher Education. All rights reserved.

Dental Comparison 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) © 2012 McGraw-Hill Higher Education. All rights reserved.

Hair Document by photos, the evidence log, and by diagram where the hairs were recovered. Do not submit wet hairs to the lab; they should be allowed to air dry. If they are firmly attached to an object, leave the hairs intact and submit the object. When visible hairs are not firmly attached to an object or the object is too large to submit to the lab, carefully remove them with clean tweezers. If hairs were possibly transferred to the victim’s and/or suspect’s clothing, keep their clothes apart. Package each article of clothing separately and submit to the laboratory separately. Do not overlook the potential probative value of animal hair; if a victim’s pets were present at the time of the offense, samples should be pulled from them and handled in the usual manner. © 2012 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 © 2012 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. © 2012 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? © 2012 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 © 2012 McGraw-Hill Higher Education. All rights reserved.

Tool Marks Identify the type of tool that made the mark or impression Establish the action used to operate the tool Specify the size and other characteristics of the tool Identify unusual features Establish whether two portions of a tool were ever commonly joined Establish whether the evidence is suitable for comparison purposes Determine whether “this” tool could have made “that” impression or mark. © 2012 McGraw-Hill Higher Education. All rights reserved.

Questioned Documents Handwriting and handprinting examinations There are three types of forgery: Traced forgery Simulated forgery Freehand forgery © 2012 McGraw-Hill Higher Education. All rights reserved.

Questioned Documents continued Photocopier examination Paper examination Age of documents Burned or charred paper Altered or obliterated writing Writing instruments mechanical-impression instruments Typewriting © 2012 McGraw-Hill Higher Education. All rights reserved.