 |  Criminal Investigation, 8/e Charles R. Swanson,
University of Georgia
Neil C. Chamelin,
Assistant State Attorney, Second Judicial Circuit
Leonard Territo,
University of South Florida- Tampa
Physical Evidence
Chapter OutlineI. CLASS VERSUS INDIVIDUAL CHARACTERISTICS(see Slide 3-2) A. Class Characteristics When the characteristics of physical evidence are common to a group of objects
or persons, they may be termedclass. Regardless of how thoroughly examined,
such evidence can be placed only into a broad category; an individual identification
cannot be made because there is a possibility of more than one source for the
evidence. B. Individual Characteristics Evidence with individual characteristics can be identified as originating with
a particular person or source. II. UNKNOWN/QUESTIONED AND KNOWN SAMPLES Much of the work of forensic science is in making comparisons of various types
of samples. There are specialized terms to refer to these samples and it is
important to' know what they mean so you can communicate with the laboratory
and understand lab reports. At the most general level, comparison samples may
be from unknown/questioned or known sources, each of which have three sub-categories. A. Unknown/Questioned Samples 1. Recovered crime scene samples whose source in question. 2. Questioned evidence that may have been transferred to an offender' during
the commission of a crime and taken away by him or her. 3. Evidence from an unknown/questioned source which can be used to link
multiple offenses together which were committed by the same person, tool, or
weapon. B. Known Samples 1. Standard/reference samples are material from a known/verifiable source; 2. Control/blank samples are from a known source which was uncontaminated
by the crime and are used to make sure that the evidence on which the evidence
was deposited does not interfere with laboratory testing; and 3. Elimination samples, which are taken from a source known to have had
crime scene to be used to compare with unknown samples of the same type from
that scene. III. SOIL AND POLLEN A. Soil is the natural accumulation of earth materials, such as weathering
rocks, minerals. and decomposing plants, along with pollen. 1. Soil examinations can determine whether soils share a common origin by
comparing color, texture, and composition. 2. Although it is class characteristic evidence, the analysis of soil evidence
can help focus investigations and discredit alibis. 3. The pollen in soil or on plants and grass can also be very significant
in determining whether or not a suspect was at the scene. B. Locating and Handling Soil Evidence (See Slide 3-3) Soil evidence may be important when the suspect drives or walks on unpaved
areas, so that it is picked up by tire treads or the bottom of shoes and cuffs
of the pants. It may also be recovered in a number of other places, such as
the floor board of the subject's car or on articles in the trunk of his vehicle,
including shovels and blankets. C. Shoe/Footwear Foot, and Tire Impressions Shoe/footwear foot, and tireprintsare common types of evidence, as are
foot and tire impressions. D. Preserving Shoe/Footwear Prints Footwear prints may, or may not be readily visible. If they are not immediately
apparent, turn the lights off and search for them using a flashlight. E. Footprint Recovery There are several methods by which the footwear prints can be recovered. The
best approach is to send the original evidence to the lab. F. Comparing Shoe Print Evidence SICAR, is a software package which classified, archives, and identifies shoe
prints. G. Preserving Footwear Impressions (see Slides 3-4 and 3-5) As in the case with footwear prints, the location of footwear impressions should
be photographed as part of the general scene and then with a scale. H. Preserving Shoe Impressions in Snow Dental stone is also the preferred material for casting impressions in snow,
replacing the more difficult and time consuming process of using sulfur, which
has to be heated. IV. PAINT (See Slide 3-6) A. During many investigations there is a possibility of encountering paint
which has accidently or by force been transferred from one object to another. V. GLASS Glass is important as physical evidence because of the frequency with which
it is encountered. A. It is essential that the crime scene technician and investigator understand
the ways in which glass reacts to force. B. Handling Glass Evidence Tape should not be used to collect glass evidence and any processing for latent
prints is ordinarily done in the laboratory. VI. FIBERS, CLOTH FRAGMENTS, AND IMPRESSIONS (see Slide 3-7) A. Fibers are of greater value as evidence than are rootless hairs because
they incorporate such variables as material type, number of fibers per strand,
number of strands, the thickness of fibers and strands, the amount and direction
of twists. VII. STRING, CORD, AND ROPE A. String, cord, and rope evidence is usually found in robbery, criminal
homicide, rape and abduction cases. VIII. FINGERPRINTS A. Several different parts of the body such as palms, fingers, toes and
the soles of the feet have friction ridges that can for a"fingerprint." B. There are three broad categories of latent fingerprints: (See Slide 3-8) 1. Plastic printsare created when fingers touch against some material such
as a newly painted surface, the gum on envelopes and stamps, oil films, explosives,
thick layers of dust, edible fats, putty, and adhesive tape. 2. Contaminated/visible printsresult after a finger, contaminated with foreign
matters such as soot, oils, face power, ink, and some types of safe insulation,
touches a clean surface. 3. Latent/invisible printsare associated with the small amounts of body
perspiration and oil that are normally found on the friction ridges. C. Basis of Identification of Fingerprints The ridge detail of fingerprints including ends of ridges, their separations,
and their relationship to each other constitutes the basis for identification
of fingerprints. D. Conditions Affecting the Quality of Latent Fingerprints (See Slide 3-9) 1. The surface on which the print is deposited. 2. The nature of the material contaminating the fingerprint. 3. Any physical or occupational defects of the person making the print. 4. How the object on which the prints appear was handled. 5. The amount of the contamination. E. Locating Latent Fingerprints Latent prints are such valuable evidence that extraordinary efforts should
be made to recover them. F. Methods of Developing Latent Fingerprints (See Slides 3-10 and 3-11) There are numerous ways to develop latent prints. Five of these with which
investigators should be familiar are: 1. Traditional Powders. Commercially prepared traditional powers come in
a number of colors, including black, white, silver, red, and gray. 2. Fluorescent Powders. Low concentrations of some naturally occurring substances
will cause a latent print to fluoresce or glow, under laser, alternative light,
or ultraviolet illumination. 3. Chemicals. A variety of chemicals are used to develop and enhance latent
prints. a. Amido black: Amido black is a dye sensitive to properties in blood and
may be used with contaminated/visible prints involving blood. b. Crystal violet: Crystal violet is used to develop latent prints on the
adhesive side of almost any kind of tape. c. Iodine: One of the oldest and most proven methods of developing latent
prints on both porous particularly paper and nonporous surfaces is iodine fuming. d. Ninhydrin: This chemical is also used to develop latent prints on paper
and cardboard, producing purplish prints. e. DFO (1, 8-diazafluren-9-one): While it functions similarly to ninhydrin,
DFO is about three times more effective than it is in developing latent prints
on paper. f. Small-particle reagent (SPR): SPR is used for developing latent prints
that have been immersed in water, as when a perpetrator has attempted to dispose
of a firearm used in a crime by throwing it into a river or lake. g. Rhodamine 6G: This is an excellent fluorescent chemical dye to use on
metal, glass and leather G. Superglue Fuming (See Slide 3-12) Superglue fuming was developed in 1978 and its use rapidly spread. H. Marking and Identifying Print Lifts When a latent print has been developed, lifted, and placed on a card, it is
necessary that the card be properly identified. I. Developing Latent Fingerprints on Bodies For the most part, the history of trying to locate and develop latent fingerprints
on the bodies of deceased victims is one of failure. However, glue fuming of
the deceased’s body, followed by application of magnetic powers is a recommended
approach to developing latent prints on the bodies of deceased victims. J. Collecting and Preserving Latent Prints Once a print is found regardless of whether it is plastic, contaminated/visible,
or a latent that has been developed with powers it should be photographed immediately
with a rigid scale in view. IX. DENTAL EVIDENCE (See Slide 3-13) Forensic dentistry is a speciality that relates dental evidence to investigation. A. History The teeth and facial bones are a major means of identifying skeletal remains
and have been used by anthropologists for many years. B. Dental Identification Dental records include, but are not limited to, dental X-rays, dentagrams,
dental charts, prosthetic molds, and dental cases. C. Bite-Mark Evidence Investigators must be particularly alert to the possibility that bite-mark
evidence exists whenever the are working violent-crime and child-abuse cases. X. HAIR A. An initial step in the forensic examination of hair is to determine whether
or not it is of human origin. B. Human hair evidence is most frequently found in violent crimes. A nujber
of conclusions can be established. XI. BLOOD (See Slides 3-15 and 3-16) At crime scenes, blood may be encountered in sizes from small drops to large
pools, in states ranging from fresh to dried, or somewhere in between those
points, and in as many places as we can name, including on floors, walls, ceilings,
clothes, weapons, the suspect's and victim's bodies, and the exteriors and interiors
of vehicles. Blood is very important in DNA analysis. A The Appearance of Bloodstains (See Slide 3-17) If blood at the crime scene is fresh and relatively uncontaminated, identifying
it as such is not difficult. Hemident can be used to do a preliminary field
test for the presence of blood. B. Using Bloodstains to Reconstruct the Crime We know that blood stains may take many forms at a crime scene. These forms
are not random, but are produced by factors such as the type, location, and
number of wounds inflicted, the type of weapon involved, movements by victims
trying to escape, defend themselves, or attack the offender, changes in the
location of the victim's body due to the offender or someone else moving it,
and continuing post-mortem violence to the body by the offender, suggesting
a state of rage by the killer and possibly someone who knew the victim. C. Locating Blood Evidence The places at which the investigator will find blood stains are virtually unlimited. D. Handling Blood Evidence Prior to handling any blood evidence, its location and physical state, e.g.,
fresh, must be documented by some combination of notes, diagrams, videotaping,
and photography. 1. Collection and Handling of Fresh and Dried Blood on a Person. When there
is fresh blood, absorb it on a clean cotton cloth or swab. 2. Fresh Blood on Surfaces or in Snow or Water. The procedures for collecting
and handling fresh blood from most surfaces are exactly the same as those described
in the previous section. 3. Fresh and Dried Bloodstains on Garments and Objects. You should allow
fresh blood stains on garments to naturally air dry and then the clothing should
be carefully folded with the crusts intact. Do not fold clothing in a way which
creases blood stains as this may cause them to become dislodged. As you fold
the clothing, place clean paper between each layer. Usually, bloodstained garments
are found at the crime scene or retrieved from a hospital’s emergency room. 4. Other Considerations in Handling Blood Evidence. During warm weather,
especially during daylight hours, blood evidence should not be locked in the
interiors of cars or in their trunks because of potential rapid degrading of
the evidence. 5. Laboratory Determinations XII. LIP COSMETICS AND LIP PRINTS A. Lip cosmetics include products such as lipsticks, glosses, balms, liners,
and lipstick sealants. XIII. FIREARMS (See Slides 3-18 and 3-19) A. Firearms evidence is commonly encountered in murder, aggravated assault,
robbery, rape, drug, kidnapping, and suicide cases. B. The laboratory examination of firearms evidence may be able to provide
the answers to the following questions. 1. Was this bullet fired from this weapon? 2. What else can be learned from the bullet? 3. What determinations can be made from cartridge cases? 4. What miscellaneous determinations can be made by examinationoffirearms evidence? C. Collecting Firearms Evidence A cardinal rule in handling weapons at the scene of a crime is that they should
never be picked up or moved until they have been photographed and measurements
made for the crime scene sketch. D. Marking Firearms Evidence For identification purposes, The FBI does not recommend marking directly on
cartridges, shell cases, bullets and fragments, shotgun shells and cases firearms,
magazines, clips, and related materials. XIV. TOOL MARKS A. For forensic purposes, a tool mark is any impression, cut, gouge, or
abrasion made when a tool comes into contact with another object. XV. QUESTIONED DOCUMENTS (See Slide 3-20) A. Loosely defined, a document is anything on which a mark is made for the
purpose of transmitting a message. A disputed or questioned document is one
whose source or authenticity is in doubt. B. Document Examination 1. Handwriting and Handprinting Examinations. Because handwriting identification
is based on the characteristics found in a person’s normal writing, writers
of a document can often be positively and reliably identified. 2. There are three types of forgery: (See Slide 3-21) a. A traced forgery is created by tracing over a genuine signature. A forgery
of this type can be tied to the original, or master, signatures if that original
signature can be located. b. A simulated forgery is produced by the writer who learns to mimic a genuine
signature. It may or may not be possible to identify the forger, depending on
the extent to which the suspect’s normal handwriting characteristics. c. A freehand forgery represents the suspect’s normal handwriting, with
no attempt to mimic the style of the genuine signature. 3. Photocopier Examination. This involves splicing two documents together
by photocopying them to form a totally new and illegitimate, but legal appearing
document. 4. Paper Examinations. This type of examination can yield several different
results. It is possible to positively match the torn edges of paper. 5. Age of Documents. 6. Burned or Charred Paper 7. Altered or Obliterated Writing. Many types of documents are easily altered.
For example, bank deposit slips commonly have a line"less cash received." 8. Mechanical-Impression Examination. A questioned document that is produced
by mechanical impression can be compared with genuine printed documents to determine
if it is counterfeit. 9. Typewriting. Typewriter brands of manufacturers can be determined from
a typed document. The individual typewriter may also be identified. 10. Computer Printers: Dot Matrix, Ink-Jet, Laser, Wax-Jet, Thermal; Fax
Machines. Printer identification is a tough proposition. It may be possible
to identify the make and model of a printer and to identify a page as having
come from a specific printer, although most often this cannot be done. |
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2002 McGraw-Hill Higher Education