Chapter 4 discusses physical evidence class characteristics, highlighting the difference between class and individual characteristics, particularly in relation to soil and forensic evidence. It covers various types of evidence, such as fingerprints, firearms, and documents, detailing collection and analysis methods, along with their significance in investigations. The chapter emphasizes the importance of thorough crime scene processing, investigator health and safety, and proper documentation to achieve successful prosecutions.

1. Chapter 4 – Physical Evidence
Class Characteristics
When the characteristics of physical evidence are common to a
group of objects or
persons, they may be termed class. 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.
Individual Characteristics
Evidence with individual characteristics can be identified as
originating with a
particular person or source.
Soil is the natural accumulation of earth materials, such as
weathering rocks,

2. minerals, and decomposing plants, along with pollen.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.
Locating and Handling Soil Evidence
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.

3. 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.
Comparing Shoe Print Evidence
SICAR is a software package which classifies, archives, and
identifies shoe prints.
Preserving Footwear Impressions
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.
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.
Photographs of footwear impressions at a crime scene
In the first photo only the impressions are shown

4. In a subsequent photo a ruler will be added to show sizes
Later casts will be made of the impressions
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.
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 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

5. vehicle has been crashed or wrecked. Advances in lamp filament
technology
now allow the investigator to determine this question.
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.
Several different parts of the body—such as palms, fingers, toes
and the
soles of the feet—have friction ridges that can be used for a
“fingerprint.”soles of the feet—have friction ridges that can be
used for a “fingerprint.”
There are three broad categories of latent fingerprints:
1. Plastic prints are 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.

6. 2. Contaminated/visible prints result 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 prints are associated with the small amounts
of
body perspiration and oil that are normally found on the friction
ridges.
Conditions Affecting the Quality of Latent Fingerprints
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.
Methods of Developing Latent Fingerprints
There are numerous ways to develop latent prints. Five of these
with which
investigators should be familiar are:

7. 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:
b. Crystal violet:
c. Iodine:
d. Ninhydrin:
e. DFO
f. Small-particle reagent (SPR):
4. Superglue Fuming
5. Visualization under Laser, Alternative Light, and Ultraviolet
Illumination
The term reflected ultraviolet imaging system (RUVIS) is the
generic name for a

8. class of lighting and imaging systems that have been
increasingly used in the past
several years.
Latent prints are such valuable evidence that extraordinary
efforts should be
made to recover them.made to recover them.
Superglue fuming was developed in 1978 and its use rapidly
spread. In this
photograph a portable superglue fuming chamber is used to
process the inside and
the outside of the car. It is more efficient for processing larger
objects.
Forensic dentistry is a specialty that relates dental evidence to
investigation.
The teeth and facial bones are a major means of identifying
skeletal remains
and have been used by anthropologists for many years.
Dental records include, but are not limited to, dental X-rays,
dentagrams,

9. dental charts, prosthetic molds, and dental cases.
Investigators must be particularly alert to the possibility that
bite-mark
evidence exists whenever they are working violent-crime and
child-abuse
cases.
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.
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 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.

10. 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.
These are common sources of blood and DNA evidence that
investigators need to
be aware of in conducting crime scene searches.
Below shows the proper use of Hemident in a presumptive or
preliminary
field test for blood.field test for blood.
Firearms evidence is commonly encountered in murder,
aggravated assault,
robbery, rape, drug, kidnapping, and suicide cases.
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?

11. 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
examination of
firearms evidence?
When a bullet passes through the barrel of a weapon distinctive
scratches are
caused.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.
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. Social security numbers are an
important source of
identification in America.

12. 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.
There are three types of forgery:
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.

13. There are several different methods used in order to identify
questionable
documents. These include:
Photocopier examination
Paper examination
Age of documents
Burned or charred paper
Altered or obliterated writing
Writing instruments
mechanical-impression instruments
Typewriting
Chapter 3 – Investigators, the Investigative Process, and the
Crime Scene
A crime is the commission (the “doing”) or omission (failing to
do) of any act which is
prohibited or required by the penal code of an organized
political state.
B. In most states a felony is an act punishable by imprisonment

14. for a
term of one or more years or by death.
C. Generally, violations of the criminal code which are not
felonies are
designated as misdemeanors, lesser offenses which may be
punishable by a fine
not to exceed $500 and/or imprisonment for not more than one
year.
D. Some states have a third crime category called a violation,
e.g.,
criminal littering, which are punishable only be a fine of not
more than $250.
An investigator is someone who gathers, documents, and
evaluates
evidence. evidence.
The investigator is someone with strong professional training
and solid
experience who by carefully completing every appropriate step
in an
investigation leaves nothing to chance.
Investigators must use both inductive and deduction reasoning.
The investigative process had the following objectives:

15. 1. To establish that a crime was actually committed.
2. To identify and apprehend the suspects(s).
3. To recover stolen property.
4. To assist in the prosecution of the person(s) charged with the
crime
The actions taken at the scene of a crime immediately following
its detection
and reporting constitute what is termed the preliminary
investigation.and reporting constitute what is termed the
preliminary investigation.
1. Receipt of Information and Initial Response
2. Emergency Care
3. Crime Scene Control
4. Issue A Be On The Lookout Alert for Suspects
5. Crime Scene Determination
6. Evidence
7. The Incident/Offense Report
Follow-up investigation is the effort expended by the police in
gathering information

16. subsequent to the initiation of the original report until the case
is ready for
prosecution or closed.
Crime scenes vary with the amount of physical evidence which
is ordinarily
expected to be recovered; a murder scene in a motel room will
yield more expected to be recovered; a murder scene in a motel
room will yield more
physical evidence than a yard from which a lawnmower was
stolen. At the
most basic level, a crime scene is the location where the offense
was
committed.
There are several ways to think about what a crime scene is.
1. Criminal incident may have more than one crime scene.
2. Based on size, there are macroscopic and microscopic
scenes.
3. Other useful ways of thinking about crime scenes are based
on the type of
crime (larceny versus aggravated assault), the location (indoors
or outdoors),
the condition of the scene (organized or disorganized), and the
type of

17. criminal action (active or passive).
Crime-scene investigators examine blood-stained clothes before
placing them in an
evidence bag.
The work at the crime scene is divided into three functions: 1)
overall coordination
of the scene; 2) technical services; and 3) investigative services.
A. Overall Coordination
Ordinarily, this first function is vested in the senior investigator
at the scene and she
or he will have the final responsibility for what is done at the
scene and what types
of additional resources will be requested.
B. Technical Services
This function is the responsibility of the ranking representative
of the department’s
central crime laboratory or its crime scene processing unit,
along with any
subordinate specialists who are assigned to the scene.
C. Investigative Services
Investigative services include interviewing witnesses,
conducting and documenting
the neighborhood canvass discussed earlier, a field interrogation

18. of the suspect if in
custody, and carrying out and recording the results of a vehicle
information canvass.
There are three broad categories of evidence in which
investigators have a
particular interest: 1) corpus delicti; 2) associative; and 3) trace
evidence.particular interest: 1) corpus delicti; 2) associative;
and 3) trace evidence.
An evidence recovery log is a chronological record of who
found what evidence,
where, witnessed by whom, and notations about other ways the
evidence may have
been documented, e.g., photography
The evidence recovery log is an important document which
records all The evidence recovery log is an important document
which records all
pieces of physical evidence found at a crime scene. This is
critical if the
case is to be successfully prosecuted later.
Without control, a life might be lost, evidence destroyed,
assignments overlooked,
or the investigation conducted in a generally slovenly manner.

19. In processing the crime scene, it is necessary to keep both
known facts and
inferences in mind. This facilitates the reconstruction of the
offense and inferences in mind. This facilitates the
reconstruction of the offense and
identification of the perpetrator’s method of operation, suggests
the possible
existence of certain types of physical evidence, and assists in
establishing
appropriate lines of inquiry.
In approaching the point of focus, minute, but extremely
important evidence may be
altered or destroyed, the area to be searched may be too rapidly
defined, and other
areas that might be fruitfully explored are overlooked or given
only a cursory
examination.
The rule of inclusiveness dictates that every available piece of
evidence be
obtained and where there is a question as to whether a particular
item obtained and where there is a question as to whether a
particular item

20. constitutes evidence be defined as such.
Document of the crime scene is a constant activity, starting with
the rough,
shorthand record created by field notes. In lesser offenses, a
single officer may be
the only representative of the police department at the scene.
Thus, everything
which is learned will be a result of his or her investigation. In
such cases, the only
documentation which may exist is the officer’s field notes and
the Incident/Offense
report.
There are numerous threats to investigators health and safety.
A. Infectious Diseases
1. HIV/AIDS
The HIV virus is a blood-borne pathogen which is also present
in other bodily fluids.
2. HIV/AIDS and Investigators
At crimes, accidents, and other scenes with a potential or known
HIV risk
investigators should have certain knowledge and employ self-
protection techniques.
3. Hepatitis B and C

21. Hepatitis B (HBV) is the most common serious disease in the
world and it is the
leading cause of liver cancer.
4. Tuberculosis
Tuberculosis (TB) is a chronic bacterial infection which is the
leading infectious
disease killer in the world; it is spread by the air and usually
infects the lungs,
although other organs may be involved.
B. The Americans with Disability Act (ADA)
Investigators who contract such infectious diseases may be
covered by federal
Americans with Disability Act (ADA), which makes it illegal to
discriminate against
otherwise qualified employees in employment actions—such as
assignments and
promotions—solely on the basis that an investigator is thought
to have or actually
has a covered disability
The purpose of the crime scene search is to obtain physical
evidence useful in establishing

22. that, in fact, an offense has been committed; identify the
method of operation employed by that, in fact, an offense has
been committed; identify the method of operation employed by
the perpetrator; reduce the number of suspect; and identify the
perpetrator.
A. The Five Major Considerations
1. Boundary Determination
In terms of the boundary of the crime scene, it is useful to think
of an inner perimeter and an
outer perimeter.
2. Choice of Search Patterns
There are five fundamental search patterns from which the
crime scene coordinator may
select.
3. Instruction of Personnel
Even when the same type of criminal offense has been
committed, the variation among
crime scenes may be enormous. Thus, it is of paramount
importance that the crime scene
coordinator call together all those individuals who will be, in
various capacities, processing
the scene and share with them all of the available information
concerning the case.
4. Coordination
One of the most important responsibilities of the person in
charge of the crime scene is to
integrate the efforts of those assigned to the technical and

23. investigative service functions,
along with ensuring the timely flow of pertinent information.
5. Documentation
It is important to thoroughly document all aspects of the crime
scene search.
The crime scene coordinator may choose from a variety of crime
scene search
patterns based upon the type and size of the crime scene.
21