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Forensic
Examination and Analysis of Physical Evidence
Author:
Dr Steven Dobrowski
This
page gives a synopsis for each of the lecture and practical
sessions for this second year module which focuses on the
methods of detection and chemical enhancement of common
crime scene marks and stains. The module builds on the
knowledge acquired in the "Introduction
to the Principles of Forensic Science" first year
module. Below each synopsis you will find a link to the full
lecture notes on other pages. These notes include the
material delivered in the undergraduate classes together
with questions for you to consider and suggested reading.
The pages are aimed at students studying on the degree for
Chemistry with Pharmaceutical and Forensic Science but can
be accessed by any student or staff member of the University
of Bradford both from on and off campus.
Please
direct any questions to me by email.
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This
course is divided into the following nine
sessions:
timetable |
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Session
1 |
Dactylography
- Science at your Fingertips |
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Session
2 |
Fingerprint
Classification Systems |
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Session
3 |
Forensic
Practical 1
Fingerprint Classification
Earology - the Basics of Earmark Examination |
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Session
4 |
Skin
- Structure and Function
Latent Marks - Their Origin |
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Session
5 |
Enhancement
of Latent Marks - Optical Methods
Types of Fingerprint Fluorescence |
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Session
6 |
Contact
Trace Materials - Body Fluids
Enhancement of Stains in Body Fluids - Chemical
Methods |
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Session
7 |
DNA
Profiling
Enhancement of Latent Marks - Chemical Methods |
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Session
8 |
Blood
Spatter Examination
Forensic Practical 2 - Enhancement of Latent and
Patent Marks |
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Session
9 |
Assessed
Practical |
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SESSION
1 |
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Dactylography-Science
at your fingertips
History
of Fingerprints
These notes introduce you to the history behind the
study of fingerprints beginning with examples of when
the distinctiveness of marks on hands was recognised to
the development of a systematic method of
classification.
Fingerprint
Identification
The principles of fingerprint identification, now well
established, are applied the world over in more or less
the same way. This lecture introduces the basic
principles of individualisation of fingerprints,
beginning with the recognition of characteristic
patterns that form arches, loops and whorls and the
determination of ridge characteristics to the
application of the principles in fingerprint
examination.
Notes:
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SESSION
2 |
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Fingerprint
Classification Systems
Full
sets of fingerprints and even sets obtained from persons
with missing or deformed digits can be classified. This
lecture takes you through the Henry and NCIC
classification systems and how to interchange them. The
methods or pattern locus, ridge counting and tracing that
form integral parts of classification systems are also
covered.
Notes:
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SESSION
3 |
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Forensic
Practical 1
Fingerprint
Classification
You
will apply the principles acquired in the previous
sessions to the classification of fingerprints you have
obtained from yourself on previous occasions and in this
session, and to fingerprints of an unknown origin
 Earology
- the Basics of Earmark Examination
History
of Earmark Examination The laboratory
script includes notes introducing you to the history
behind the study of earmarks beginning with the original
anthropometric system devised by Bertillon to the
development of a systematic method of classification.
Earmark
identification In humans, the process
includes the examination of the external pinna, the
visible part of the outer ear. The external pinna, made
of cartilage tissue has the function of channelling
sound waves into the external auditory meatus, which in
turn directs sound waves onto the tympanum (eardrum).
The principles of earmark identification are more or
less well established, and have been used successfully
to facilitate prosecution of cases through the courts.
This lecture introduces the anatomy of the external
pinna and the basic principles of individualisation of
ears and shows how an earmark is systematically examined
to determine possible ownership. You will carry out
recovery of earmarks, and using Ianarelli's method,
attempt to match an known and unknown mark.
Notes:
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SESSION
4 |
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Skin
- Structure and Function
A
series of lectures on the chemical and physical
enhancement of latent marks begins in this session with
a review of the structure and function of skin
and the types of glands in skin responsible for
secretions that form latent deposits and marks.
The
information presented in the class as a lecture is
available on the web through the link below. More
extensive information is available in notes in portable
document format (pdf) which can be accessed from the web
page-based lecture.
Latent
Marks - Their
Origin
In
the context of the search for fingerprints or other
marks at a crime scene or on items subjected to visual
examination, latent marks are those which are not
visible by direct observation. The word latent
has several meanings, including potential and undeveloped,
concealed, hidden and dormant.
A latent mark is, therefore, one which is hidden and has
the potential to be developed and revealed. This session
explores, not the types of latent marks that may be
encountered in forensic investigation, but the nature of
the substances secreted by the body which, when
transferred to a surface, form the latent mark.
The
information presented in the class is available more
extensively as notes in portable document format (pdf).
Notes:
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SESSION
5 |
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Enhancement
of Latent Marks - Optical Methods
Types
of Fingerprint Fluorescence
The
composition of latent images has been discussed in an
earlier section. How are these observed on items
submitted as physical evidence to the police fingerprint
bureau or laboratory or at the scene of a crime? Often
difficult to observe, the forensic specialist has at his
or her disposal techniques of illumination and a range
of substances that can be applied to the latent image
bearing surface to optically enhance or chemically
enhance the latent marks, respectively. This session
introduces you to the process of enhancement of latent
images and to the photochemical process of fluorescence.
Notes:
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SESSION
6 |
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Contact
Trace Materials - body fluids
This
session, delivered by a visiting speaker from the Wetherby
Laboratories of the Home Office Forensic Science Service,
introduces aspects of the search and recovery of stains on
(typically) garments recovered from victims and suspects
involved in serious crime such as rape and murder. The
importance of preservation of samples which are
susceptible to thermal, physiological or bacteriological
degradation is emphasised and the processes of search and
recovery and of presumptive testing employed in the
forensic laboratory are demonstrated. The chemistry of the
presumptive tests is dealt with in a later Session.
Enhancement
of Stains in body fluids - Chemical Methods
The
reactions of chemical substances with components of blood
and semen are discussed in these notes.
Notes:
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SESSION
7 |
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DNA
Profiling
This
session, delivered by a visiting speaker from the
Forensic Science Service, Wetherby Laboratories,
introduces the topic of DNA profiling. The talk covers
(1) the basics of DNA - what it is, its constitution and
structure and how it relates to genes and chromosomes,
(2) how it can be obtained from body fluids and
processed for subsequent analysis, (3) the analytical
method and (4) interpretation of the genetic profile.
The talk assumes no prior knowledge of DNA and the
technology of profiling and is a good primer for more
extensive study of the subject.
Enhancement
of Latent Marks - Chemical Methods
The
enhancement of latent marks includes both physical and
chemical methods. These notes deal with the principles
and methods of chemical fingerprint enhancement, the
selection of appropriate methods and the underlying
physicochemical processes and chemical mechanisms for
some of these. The notes are available directly from
this page as pdf files. You will need Adobe Acrobat
Reader to view the files.
Notes:
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SESSION
8 |
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Blood
Spatter Analysis
Blood
is one of the most significant and frequently encountered
types of physical evidence at scenes of violent crimes.
The circumstances and nature of violent crimes involving
the shedding of blood produce a wide variety of blood
stains and spatter patterns.
Notes:
Forensic
Practical 2 - Enhancement of Latent and Patent Marks
In
this laboratory session you will put to practice some of
the techniques of chemical (and where appropriate,
physical) enhancement applied to latent fingermarks and
marks having the appearance of blood. The practical script
can be downloaded directly from this link.
Notes:
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SESSION
9 |
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Forensic
Practical 3 - Assessed Practical
In
this practical
you will be given a case scenario and will have to use any
and all of the forensic techniques you have acquired (both
this year and last) in performing appropriate forensic
examinations. You will write up Case Notes during the
session and an Expert Statement during the vacation. Both
your Case Notes and Statement will be submitted for
assessment.
In
the real world, the forensic examination may be carried
out by an assistant forensic scientist and the Expert
Statement written-up by another, usually a Reporting
Officer in a UK Forensic Science Service Laboratory. Your
Case Notes will need to be complete and accurate and your
Statement of a quality suitable to support the giving of
Evidence in Chief. Next year, you may well be questioned
on this Statement under conditions of cross-examination!
There
are no on-line notes for the assessed forensic practical |
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