AFTE
2006 - Tuesday June 27
Sunday |
Monday |
Tuesday |
Wednesday |
Thursday |
Banquet |
Friday |
Exhibitors
Morning Session
Afternoon Session
Workshops
After-hours
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TOPIC & PRESENTER |
AREA/ROOM |
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3D Imaging:
Targeting Better Bullet Results
Alain Beauchamp, Forensic Technologies Inc.
Montreal, Quebec, Canada
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MMC Grand
Ballroom
Side A |
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Objectives:
Earlier ballistic comparison relied on
comparison of 2D signatures extracted from
grayscale imaging; with 3D imaging the
topographic profiles of the surface are used in
conjunction with 2D signatures in order to
increase matching accuracy of comparisons. This
presentation will explore some of these
opportunities and present results of a database
performance study.
Methodology:
Forensic Technology, has developed a new
automated ballistic comparison system called
BulletTRAX 3D, this technology uses 3D confocal
microscopy to image and compare bullet evidence.
The introduction of 3D imaging technology to
this field has opened up new avenues for
ballistics comparison that have never been
available to the scientist before now.
Simplified imaging of ballistics evidence,
increased comparison accuracy, quantitative
measures of the surface topology at the
nanometer level of precision, and developing
quantitative measures will significantly help
firearms experts.
Earlier ballistic comparison systems relied on
comparison of 2D signatures extracted from
grayscale imaging; with 3D imaging the
topographic profiles of the surface are used in
conjunction with 2D signatures in order to
increase matching accuracy of comparisons. This
presentation will explore some of these
opportunities and present results of a database
performance study.
Results:
This presentation will explore some of these
opportunities and present results of a database
performance study.
Conclusions:
Results & Conclusions will be provided upon
completion of the presentation.
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Magazines:
Their Marks and Their Meaning
Charles M. Clow, Southwestern Institute of Forensic
Sciences
Dallas, TX
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MMC
Grand Ballroom
Side B |
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Objectives:
Firearm magazines, like other tools, have the
potential to produce toolmarks on cartridge
cases. These marks and their uniqueness have
come into question in the legal arena. This
study will:
- Review the manufacturing
processes involved in magazine manufacture.
- Identify the areas of the
magazine that have an opportunity to make
marks.
- Identify situations that
could influence the production of magazine
marks.
- Produce magazine marks
with ten consecutively manufactured Hi-Point
magazines.
- Produce magazine marks
with ten “same lot” magazines manufactured
by Check-Mate Industries, Inc.
- Review the findings of
the microscopic comparison of the magazine
marks produced by consecutive and “same lot”
manufactured magazines.
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Variation in
Ejection Port Marks from the Same
Firearm
Beta Tam, Los Angeles Police Department
Los Angeles, CA
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MMC Grand Ballroom
Side B |
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Objectives:
Provide a visual discussion on how much ejection
port marks on cartridge cases fired from the
same firearm could be different from each other
so that incorrect elimination could be avoided.
Methodology:
1. Comparing ejector port marks for over fifty
fired cartridge cases.
2. Observing the firing marks with different
prospective.
3. Locating the identification marks on
individual cartridge case.
4. Combine ejection port marks on different
cartridge cases together using the matching area
as orientation.
5. Study the whole length of the combined marks
and appreciate the differences.
Results:
1. Different prospective of the marks revealed
different types of marks seen.
2. The full length of the combined ejection
marks is at least a couple of times longer then
individual ejection ports marks.
3. The marks have a striated area and also some
impressed area too.
4. The texture of the marks varies from one end
to the other.
Conclusions:
1. The contact area around the ejector port is
so inconsistent that elimination is almost
impossible.
2. When multiple cartridge cases are available,
go through the whole length with different
orientation to ensure identification is not
missed.
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A Tool for
Classifying the Mechanisms of Penetrating
Trauma
David Andrew, Queensland Health
Toowoomba, Queensland, Australia
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MMC Grand Ballroom
Side A |
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Objectives:
To have a tool to describe the forms of
penetrating trauma for descriptive and
statistical analysis.
Methodology:
Define penetrating trauma by type of penetrating
tool and the force propelling it.
Results:
A flow chart that describes the mechanism of
injury.
Conclusions:
A useful tool to help define the type of
protective item needed against a specific
threat.
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A
Classification Method for the Mechanisms of
Penetrating Trauma
David Andrew, Queensland Health
Toowoomba, Queensland, Australia
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MMC Grand Ballroom
Side A |
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Objectives:
When trying to defeat an adversary we must first
understand what we are trying to defeat. In body
Armour design we know what works but how do we
define/describe what a fragmentation, stab or
bulletproof vests designed to do. This method
allows us to do this. It also provides
information that is useful in an Emergency
Department or Crime Statistics reports.
Methodology:
A brainstorming session to identify the threat,
evaluating the information, hashing it out over
many months and finally a tool in the form of a
flow chart.
Results:
A Penetrating Trauma Mechanism Classification
Tool.
Conclusions:
It works for instances I and others could think
up, remember or research.
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A Numerical
Comparison Study of Five Different
Chemical Procedures Using Griess Reagents
Garry Lawrence, Centre of Forensic Sciences Firearms and
Toolmarks
Toronto, Ontario, Canada
Srinivasan Rathinam, Centre of Forensic Sciences
Firearms and Toolmarks
Toronto, Ontario, Canada
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MMC Grand Ballroom Side B |
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Objectives:
To rank five different Griess reagents
procedures in the order of most effective to
least effective. This will be done by examining
the processed test panels and assigning a
numeral value to the nitrites that have reacted
to the different Griess reagents.
Methodology:
Five sets of three test panels were created at a
distance of 18, 24, 36, 48 and 60 inches. The
test panels were then processed using the Griess
procedure with desensitized photographic paper,
Griess procedure with inkjet paper, Modified
Griess procedure with desensitized photographic
paper, Modified Griess procedure with inkjet
paper and Simplified Griess procedure. A
one-inch square grid transparent sheet was
placed over each treated test panel and the
nitrites that reacted to the Griess procedures
were given a numerical value in a selected grid.
The numerical values were then totaled for each
procedure and were listed in a ranking order of
highest to lowest.
Results:
To be determined before the 2006 AFTE Seminar.
Conclusions:
To be determined before the 2006 AFTE Seminar.
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Surface
Topography Analysis for a Feasibility Assessment
of a National Ballistics Imaging Database
Dr. Theodore Vorburger, National Institute of Standards
and Technology
Gaithersburg, MD
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MMC Grand Ballroom
Side A |
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Objectives:
We report on a study to assess the feasibility
of a national ballistics database of casing and
bullet images. The purpose of such a database
would be to provide a reference collection of
ballistic images with which casings or bullets
found at the scene of a crime may be compared,
with the intent of uniquely identifying the
weapon that generated the spent casing or
bullet.
Questions to address include:
• Are the markings, which an individual gun
leaves on its fired casings, unique enough to
support a national ballistics identification
system?
• How do three-dimensional (3D) topography
imaging methods compare with the optical imaging
technologies currently in use for ballistics
identification?
Methodology:
We investigated two collections of fired
casings, identified here as the De Kinder
collection and the NBIDE (NIST Ballistics
Imaging Database Evaluation) collection. The De
Kinder collection was created several years ago
to test the performance of the Integrated
Ballistics Identification System (IBIS)* in a
large database. From the De Kinder collection,
we used 70 casings, seven casings each from ten
Sig Sauer P226 guns, providing us with 70
casings for analysis. Six different brands of
ammunition had been fired by each gun as part of
that study. The NBIDE collection is a set of
test fires created by us. The statistical design
included three gun types (Sig Sauer, Ruger, and
Smith & Wesson), four guns of each type, three
ammo types, and three firing repetitions for
each ammo type taking place over three days.
We compared two image analysis methods, IBIS,
based on optical reflection microscopy, which is
widely used for forensic ballistic examinations,
and an experimental system, based on imaging of
3D surface topography, which we call NTES, for
NIST Topography Evaluation System. In addition,
the NTES system includes a correlation method
based on cross-correlation statistics. These two
systems were applied to both of the above casing
collections and compared.
Results:
The two analysis systems were compared using Top
Ten lists, color correlation charts, and other
statistical methods. For the four data sets (De
Kinder Firing Pin, De Kinder Breech Face, NBIDE
Firing Pin, NBIDE Breech Face), the NTES system
scored slightly higher to significantly higher
for obtaining matches of casings fired by the
same guns. The Table below shows summary Top Ten
List performance results for De Kinder and NBIDE
casings, IBIS and NTES analysis systems, and two
casing regions. The ratios there indicate the
average number of correct matches appearing in
the Top Ten list divided by the total number of
correct matches.
Data Set
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Feature Under Comparison
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Firing
Pin |
Breech
Face |
De
Kinder
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IBIS
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3.0/6 |
1.0/6 |
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NTES |
3.6/6 |
2.8/6 |
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NBIDE |
IBIS |
3.7/8 |
5.1/8 |
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NTES |
5.6/8 |
7.9/8 |
Conclusions:
For a technology to be feasible for a very large
database, its Top Ten lists should have obtained
close to all possible correct matches in a
relatively low sample size experiment like those
described in this report. Nothing here is close
to achieving such high performance standards,
except for the NTES performance on the NBIDE
breech face impressions. Even these data fall
well short of the estimated required accuracy.
In order to perform at levels necessary for very
large databases of say 100 000 guns of the same
class, the error rates must be so low that for
experiments with only 70 or 108 casings shown
here, there should not be any overlap between
the matching and non-matching sample
distributions.
Aside from the question as to whether a large
database is feasible, the topography (3D)
measurement approach adds to the capability of
the ballistic imaging community to progressively
examine and improve ballistics matching systems.
The NTES performance on the NBIDE breech face
impressions suggests that 3D topographic methods
are a significant advance for breech face
analysis.
*Certain commercial equipment are identified in
this presentation to specify adequately an
experimental procedure. Such identification does
not imply recommendation or endorsement by NIST,
nor does it imply that the equipment are
necessarily the best available for the purpose.
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Break |
Exhibit Hall |
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Recent Changes
in United Kingdom Firearms
Legislation and the Effects on the Casework
Submissions Seen at the Forensic Science Service
Limited
Alice Walters, Forensic Science Service Limited
Firearms Section
London, United Kingdom
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MMC
Grand Ballroom Side A |
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Objectives:
In the United Kingdom there is a problem with
modified and converted air guns and blank
cartridge firing guns. The introduction of the
Anti-social Behaviour Act 2003(ASBA 2003) in
January 2004 outlawed the possession of certain
types of tandem air cartridge guns commonly
referred to as Brococks. These "self-contained
gas cartridge" guns became prohibited even in
their unconverted form, i.e. even when air guns.
This paper looks at emerging trends in converted
firearms encountered since the introduction of
this most recent legislation, such as converted
blank firing replicas of MAC10s and converted
gas guns.
Methodology:
The National Firearms Forensic Intelligence
Database was interrogated to determine which
types of converted guns are currently emerging
as trends in casework submissions.
Results:
Three emerging trends were observed:
1) Conversions of 9mm Parabellum calibre blank
cartridge firing replicas of MAC10s now firing
9mm Parabellum
cartridges in fully automatic mode
(smooth-bored).
2) Conversions of 8mm calibre Baikal IZh79 gas
pistols firing 7.65mm Browning or 9mm Short
calibre cartridges
(rifled barrels, 3L, 4R, 6R).
3) Conversions of 9mm rimmed blank calibre
Weihrauch HW94S pistols into pistols firing 9mm
Short, hybrid 9mm Short/9mm Parabellum or
modified 9mm P.A blank calibre cartridges.
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3D Consecutive Matching Stria Research
Alain Beauchamp,
Forensic Technologies Inc.
Montreal, Quebec, Canada
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MMC
Grand Ballroom Side B |
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Objectives:
BulletTRAX-3D’s three-dimensional imaging has
made available information on the bullet’s
surface that has never before been possible to
accurately and consistently read. One new
opportunity being explored by Forensic
Technology (FT) is to apply the newly readable
length, width and depth of striations extracted
from the bullet’s physical topography to
calculate groupings of consecutive matching
stria (CMS).
Methodology:
BulletTRAX-3D’s three-dimensional imaging has
made available information on the bullet’s
surface that has never before been possible to
accurately and consistently read. One new
opportunity being explored by Forensic
Technology (FT) is to apply the newly readable
length, width and depth of striations extracted
from the bullet’s physical topography to
calculate groupings of consecutive matching
stria (CMS). Using the bullet’s raw, unlit
three-dimensional surface contour as the
foundation for research eliminates the natural
variabilities that occur when the comparison
microscope is used in conjunction with side
light, which is susceptible to each individual’s
preferred angle and intensity.
Results:
This presentation will outline the research that
FT has performed to date, explain where we are
today, and forecast the development that will
continue in the future.
Conclusions:
Results and Conclusions will be provided upon
completion of the presentation.
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Cattle
Branding, Stock Theft and Poaching
Burgert Kloppers, Ballistics Unit
Forensic Science Laboratory South African
Police Service
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MMC Grand
Ballroom Side A |
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Comparison and individualization of branding
irons with stock. Various approaches and
techniques to links rhino horn, elephant tusks
to skulls. Links of animal skins and carcass
part through physical matching. |
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An Evaluation of Body Armor
Nancy D. McCombs, California State DOJ, Fresno Regional
Lab
Fresno, CA
Michael A. Appel, California State DOJ, Fresno Regional
Lab
Fresno, CA
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MMC Grand Ballroom Side A |
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Objectives:
This paper discusses the recent purchase of body
armor from a local company that is receiving
nationwide publicity for its invention of Dragon
Skin Body Armor.
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Going Further with GSR Analysis: The
Adaptation of SWG-MAT Trace Evidence Recovery Guidelines for the Analysis of Gunshot Residues on Clothing
Richard N. Ernest, Alliance Forensics Laboratory, Inc.
Fort Worth, TX
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MMC Grand Ballroom Side A |
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Objectives:
Current methods for the analysis of gunshot
residue particles on clothing rely on visual
examination followed by chemical testing. In
this paper, the author outlines the use of SWG-MAT
trace evidence recovery guidelines, as an
adjunct test to current methods, to further
recover essentially all gunshot residue
particles embedded from all surfaces of the
clothing. This information can be critical in
certain types of shooting cases (to be
discussed) to answer issues of the distance
involved in the shooting. Several case studies
from prior casework employing these techniques
will be discussed.
Methodology:
After the use of current visual examination
techniques and chemical testing for gunshot
residues is concluded, the clothing items are
examined using a variety of trace evidence
techniques such as tape lifts, scraping
techniques and vacuuming techniques. The
resultant debris isolated from the clothing may
contain numerous microscopic particles of
gunshot residue which can be examined by various
methods which will be discussed. The author will
outline the various common forms of trace
evidence debris normally isolated from gunshot
residues, and will discuss the ranges to which
some of this debris may be encountered following
the discharge of a firearm.
Results:
Trace evidence analysis of the gunshot residue
debris encountered from the firing of a firearm
may allow in certain cases for a further
characterization & determination of the range(s)
at which a firearm was fired. In certain types
of shooting case scenarios such information can
be crucial to the solving of the case.
Conclusions:
Trace evidence analysis of the gunshot residue
debris encountered from the firing of a firearm
is not a technique which should be used in every
type of shooting case, but it is a technique
which can be used in certain types (to be
discussed) which can lead to valuable or
critical information which may be useful to the
solving of a case.
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Aguila IQ Case Study in .45 ACP
Dale Justice, Bexar
County Crime Lab, San Antonio, TX
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MMC Grand Ballroom Side B |
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Objectives:
For the last several
years the Mexican manufactured ammunition
packaged under the Aguila name produces a
product line marketed as the “first intelligent
bullet”. This high velocity zinc hollow point
bullet remains intact when penetrating hard
objects and fragments in soft material. We
present a case report of a homicidal gunshot
wound resulting from a shooting with this
relatively uncommon ammunition.
A discussion of this bullets elemental
composition, fragmentation pattern, P GSR
results and test shots into a bullet resistant
vest will also be discussed. The tests were
conducted to determine:
1) If the manufacturer's performance data was
accurate.
2) The elemental composition of the bullet.
3) If the "vest piercing" claims were correct.
4) If zinc bullets create conflict with current
primer gunshot residue (P GSR) analysis
methodology.
Methodology:
Obtained ammunition through local sources
and fired tests into a water tank, cotton tube
and an older kevlar protective vest. Also
chronographed the bullets at two locations. The
firearm used(Haskell) was the closest model to
one used in a homicide (Hi Point) available in
our reference collection.
"Soft target" results were compared to x rays
and recovered fragments from the homicide case.
SEM analysis of unfired ammunition and P GSR
stubs were performed by the Trace Evidence
section.
P GSR was collected prior to firing, after one,
three and five shots.
Results:
Performance was consistent with manufacturer's
claims.
1) Broke into three or four pieces in soft
material (water).
2) Remained intact in solid material (cotton &
vest).
3) Velocity measured at over 1400 FPS at approx
9 feet.
Urban myths BUSTED! Failed to perforate the vest
at three and nine feet with direct shots. A
second angled shot at nine feet also failed to
penetrate. The impact was sufficient to caused
serious or fatal injuries without bullet
penetration.
SEM indicates the bullets are primarily pure
zinc with a few trace amounts of other
metals/minerals.
P GSR showed an abundance of zinc, which
increased with successive firing. There was a
significant rise between one and three shots
with a moderate increase from three to five.
Conclusions:
Aguila IQ bullets perform as advertised by
the manufacturer NOT as stated in cyber stories.
Although the vest was not penetrated, it is
possible to sustain fatal injuries from the
impact alone.
Criteria for evaluation of P GSR needs to be
examined to account for the zinc presence
without copper for this ammunition.
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Hawkeye Precision Borescope Improvements
Ken Harrington, Gradient Lens Corporation
Rochester, NY
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MMC
Grand Ballroom Side B |
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Objective:
Our efforts to date with AFTE have been
particularly rewarding and we have decided to
make a significant upgrade to the GRAND-AFTE kit
that has become so popular with firearm and
toolmark examiners in the last two years.
Presentation will include a few new shooting
images and an announcement of the product
improvements that we have made on your behalf.
At that time I will also announce that we will
give away a $845.00 Hawkeye Precision Borescope
Kit at the banquet to one of the AFTE members
who stops by to see a demo.
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Lunch (Provided) |
Exhibit Hall |
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TOPIC & PRESENTER |
AREA/ROOM |
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A Statistical Validation of
the Individuality of
Striated Tool Marks using Topographical Data
Anurag Jain, Intelligent Automation, Inc. - Forensic
Technology Group
Rockville, MD
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MMC Grand Ballroom Side A |
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Objectives:
Intelligent Automation, Inc. (IAI) has
undertaken a study to assess the validity of the
premise that microscopic marks found on a tool's
working surface and transferred to the tool mark
are sufficiently unique to enable a one-to-one
association between the tool and tool mark. An
integral aspect of this study was to perform
such association in an objective and
standardized manner. As part of this study, the
effect of media on the individualization and
one-to-one association between the tool and tool
mark was also investigated.
Methodology:
Our methodology combines two main elements: The
characterization of a tool mark as a
three-dimensional (3D) object, and the use of
statistical methodologies applied to a
well-defined similarity metric to quantify the
statistical difference between known matching
and known non-matching tool marks for tools
manufactured using manufacturing/finishing
methods of interest.
Results:
By comparing the statistical distributions of
similarity metric values associated with
matching and non-matching pairs of tool marks,
it was observed that striated tool marks made
from the same tool on the same media under
identical conditions could be matched decisively
while tool marks made from the same tool on
different media could be matched with a small
probability of error. In the case of
screwdrivers, the effect of variation of angle
of attack in the creation of striated tool mark
significantly affected the degree to which they
could be matched correctly. Because the approach
taken in this study relied on the use of a
quantifiable similarity metric, the results were
repeatable and objective.
Conclusions:
The results of this study provide substantial
evidence to the validity of the basic premise of
tool mark identification for striated tool
marks. This study shows that striated tool marks
created on lead by a tool such as screwdriver or
a pair of tongue and groove pliers can be
matched with a striated tool mark made on
another media by the same tool. It can also be
concluded that the topographical information of
a tool mark provides significant potential for
the identification and matching of tool marks.
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Practical Considerations for Using Sound
Level Meters to Accurately Measure Gunshot Noise
Robert G. Brauch, Larson Davis, Inc.
Depew, NY
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MMC Grand Ballroom Side B |
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Objectives:
- Review the reasons why
firearm discharge noise is measured as it
applies to Police agencies, the Military and
their related Laboratories.
- Inform the audience about
the unique acoustic properties and salient
characteristics of noise produced by firearm
discharge.
- Provide familiarity of
the ANSI and ISO standard classifications of
sensors and instruments that can be used to
measure this acoustical properties of
firearm discharge.
- Discuss the theory of
operation for these various classes of
sensors and instruments.
- Illustrate the
limitations of different measurement
systems, techniques and methods.
- Provide a checklist of
Practical Considerations when setting up a
test procedure for measuring firearm
discharge noise.
Methodology:
n/a - This is a compendium of information
compiled to provide the audience with a good
working knowledge of the issues relevant to
proper selection of test methods and tools.
Conclusions:
Given proper consideration of the theory of
measurement and operational characteristics of
various measurement systems, the investigator
will be able to determine the relative
suitability of different acoustic measurement
systems for accurately measuring gunshot noise.
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Security Threat from Bump Keys
Marc Weber Tobias, Investigative Law Offices
Sioux Falls, SD
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MMC Grand
Ballroom Side A |
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Objectives:
Define the problem of bumping of standard and
high security pin tumbler locks.
Explain the procedures for bumping 95% of the
locks in the world.
Detail the security and forensic implications of
locks being opened without any outward evidence
of entry.
Conclusions:
The vast majority of the world's pin tumbler
locks can be opened in seconds by unskilled
individuals with virtually no training or tools.
This poses a serious security problem,
especially for criminal investigators and
forensic specialists.
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PERMA-GEL: A New Synthetic Ballistic Gelatin
Dr. Darryl D. Amick, PERMA-GEL, Inc.
Albany, OR
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MMC
Grand Ballroom Side B |
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Objectives:
Describe PERMA-GEL and point out the things
which it does well, as well as some things which
it will not do. At the present time, Luke Haag
is evaluating this material very objectively and
has given me permission to use his findings.
Because PERMA-GEL is essentially a type of very
clear, synthetic rubber, it is unaffected by
water, sub-freezing temperatures, etc. I have
designed the present composition to be used at
room temperatures, at which it simulates cold (4
degrees, C) 10% ordnance gelatin quite well for
most bullet types. P-G is more elastic than
gelatin and one can therefore get more shots per
unit surface area without overlapping cavities.
Because of this superior elasticity, very large
caliber weapons may be evaluated without
"blowing up" the gel body. Also, one may
chronograph velocities of bullets upon exiting a
target, because no bits of gel are expelled to
interfere with the chronograph.
PERMA-GEL is reusable many times (at least 10)
by simply re-melting it in a 110v/1400w
electrical oven. While molten, one may
incorporate foreign objects such as bone, sinew,
etc. Also, during melting, bullet fragments and
other inert materials may be easily removed by
several different methods which I have
developed. This material may be very useful
simply as a very gentle way of stopping bullets;
i.e., it is a very simple bullet trap that any
police department, gun dealer, et al could
afford.
Results:
PERMA-GEL, Inc. is less than one year old, so we
are continuing to learn more about its
characteristics daily from gun writers, police,
sportsmen, et al. Even now, we have substantial
data on everything from .17cal to .375cal H&H
magnum, as well as some miscellaneous data on a
wide variety of shotgun pellets, arrows,
crossbow bolts, etc.
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Break |
Exhibit Hall |
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3:30 PM |
A
Statistical Analysis of Shotgun Pellets in
Flight: A Feasibility Study
Jan De Ceuster,
National Institute of Forensic Science,
Brussels, Belgium
Kevan Walsh,
Institute of Environmental Science &
Research Limited, Auckland, New Zealand
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MMC
Grand Ballroom Side A |
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Objectives:
It is well known that on the basis of shotgun
pellet pattern distribution, one can determine
shooting distance. In a purely theoretical
situation, this can be done with acceptable
accuracy. Many methods have been developed for
this purpose. However, since complete pattern
distributions are not always present at the
scene of the crime, drawing a conclusion may not
be possible. If one is able to reconstruct
statistical density functions of shotgun
patterns, complete patterns might not be needed.
To assist in this understanding, a feasibility
study was undertaken to investigate the
distribution of pellets in flight. To identify
the parameters that influence the spread of the
pellets, it has proven useful to look at the
distribution of pellets along the propagation
direction.
Methodology:
Shotshells were loaded with different colored
pellets in different locations in the shotshell.
Four shots of each load were fired and a
side-view high-speed photograph of the pellets
for each shot was taken at a fixed distance from
the barrel. These photographs were then treated
as follows: Cartesian co-ordinates of the
pellets were individually determined and their
distributions were statistically analysed for
the axis along the direction of flight
(z-direction) and the axis orthogonal to it
(y-direction). Descriptive statistics such as
histograms, boxplots and q-q plots were employed
to aid in understanding the behaviour of the
pellets. Statistical tests such as the Kruskal
Wallis test and the Shapiro Wilk test were
applied to check if group means are
significantly different and to check on the
normality of the distribution. In this study, we
used only one gun (no choke), one fixed shooting
distance and shotgun shells with identical wads.
Results:
The results were reproducible. Firstly, the y
and z co-ordinates were found to be not always
statistically correlated (thus univariate),
which justifies in this case looking at the
co-ordinates separately. The position of the
pellets along the propagation direction, with
respect to their original position in the
shotshell was examined. The different colored
pellets located in different positions in the
shotshell display quite different behaviour,
which was corroborated by statistical testing.
Along the propagation direction the results show
that the top pellets of the shotshell mostly
remain foremost but some are overtaken by the
lower-positioned pellets. The bottom layer
pellets on the other hand are projected forward
through the distribution of the other pellets
and form a high density core of the pattern.
They can be best described as normally
distributed. In the direction orthogonal to the
propagation direction, we observed no large
difference with color (and therefore location
within the shotshell) in the distributions of
the pellets. Therefore all pellets tend to
spread radially in a similar manner. However if
there is a trend, it is that the bottom pellets
are concentrated as a normal distribution in the
core of the pattern. Although statistically no
real outliers (or flyers) were found, the core
pellets from the first half of the shotshell
seem to be more likely to become flyers. Apart
from the top and bottom pellets, the bulk of
pellets is not normally distributed. They seem
to assume a bi-modal distribution as if these
pellets were pushed aside by the bottom pellets
that push through to be concentrated in the
center of the pattern.
Conclusions:
At this stage of the research it is perhaps too
soon to draw definitive conclusions, which can
be used for practical purposes. However, this
feasibility study has shown that the results are
reproducible and lead to greater insight into
the cause of the pellet spread. The results open
up the way for future experiments:
2D-photographs to get the x and y -co-ordinates
separately; photos taken at other distances, the
effect of choke, firearm, wad, etc.
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GSR on Hands - Totally Useless?
Axel Manthei, Bavarian State Bureau of Investigation
Munich, Bavaria, Germany
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MMC Grand
Ballroom Side B |
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Objectives:
It is commonly known that the presence of GSR on
the hands of a person can not solely be
considered as positive evidence that this person
has fired a firearm. We encountered a case in
which a dead person was first considered to have
committed suicide, but other evidence indicated
that it might have been a homicide. The question
we had to answer was whether it could be ruled
out that the death was a suicide. Due to the
case circumstances, the specific firearm and
ammunition involved were examined in order to
determine if the deceased had fired the shot
with their right hand (which was on top of the
firearm).
Methodology:
The GSR sample take from the hand and the sample
collected during the tests where analyzed by SEM/EDX.
Due to the design of the firearm used in this
case, GSR is ejected on the unprotected hand of
the person firing at all times. The tests were
conducted with different holding/firing
positions of the pistol. High Speed videos were
produced to show the gas dynamic acting in and
around the firearm.
Results:
In the case presented, the firearm ejected GSR
on the hand of the shooter at all times and
conditions. The victim had no GSR on their hand.
It was determined by the MD that the victim was
not able to make any movements after receiving
the shot. Therefore the evidence presented
excluded the dead person from firing the pistol
with their right hand.
Conclusions:
In very specific cases under specific conditions
- which have to be verified carefully - it can
be determined that a hand has not fired the
particular firearm.
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AFTER-HOURS
BOSTON REDSOX Game-
Tuesday Evening a large contingent of
AFTE members traveled by bus to Boston to watch
the Boston Redsox play the New York Mets at Fenway Park.
This after-hours excursion was organized by George Foley
of the Boston Police Department. Click the
image below to view pictures taken during
the trip. The window that opens can be resized to
fit your screen and doing so may allow you to see
the images in a larger format. Thank you George for a
great trip!
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