Firearm and Tool
mark identification
A GENERAL PRIMER
Genesee County Bar Association
Criminal Law Seminar-2013
COOL, ATTRACTIVE PEOPLE
REAL LIFE
CSI-BRIDGEPORT
AWKWARD NERDS
Major Historical Events in Early Firearm
and Tool Mark Identification.
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Brownsville Affray, 1907
Prof. Balthazard, 1912-Photomicrograph Comparisons
Stielow Case, 1915
Sacco and Vanzetti Case, 1920
Waite/Goddard Partnership: 1924-Use of the Comparison Bridge
Microscope
– St. Valentine’s Day Massacre of 1929
– Opening of the Chicago Crime Lab at Northwestern University in 1930
by Calvin Goddard. First ever Public Forensic Science Laboratory.
– 1932: FBI Lab opens with one person, who was an agent (Charles
Appel) trained at Northwestern by Calvin Goddard and co. Appel soon
after handled the Lindburgh baby case as a questioned document
examiner.
Scientific Studies
• 1920s-1930’s:
– In the U.S., the work of individuals such as Col. Calvin Goddard, J.
Howard Matthews, and Maj. Julian Hatcher provide study and insight
into the science supporting Firearm and Tool Mark Identification. The
examination methodology is standardized in terms of Classification
and Identification, and texts are popularized for use and training of
Firearms Examiners.
– In Europe, the work of individuals such as French Professor Victor
Balthazard, Robert Churchill, Sir Gerald Burrard, and Col. H.W.
Todhunter further the practice through study and the writing of
subject matter.
– Courts around the country (and in Europe) begin to commonly accept
forensic firearm and tool mark expert testimony by the 1940’s.
Contemporary Scientific Studies
• 1955: A.A. Biasotti completes his 97 page thesis
concerning “Bullet Comparisons—A Study of Fired
Bullets Statistically Analyzed.”
• Biasotti goes on to publish several other very
important statistical studies concerning striated tool
marks on fired bullets throughout the 50’s, 60’s, and
early 70’s.
• Other examiners expand on these studies, which
create statistical foundations for striated toolmarks.
Contemporary Scientific Studies
• 1969: Association of Firearm and Toolmark
Examiners (AFTE) is chartered. The AFTE Journal is
popularized as a peer-reviewed scientific journal
concerning the relevant field.
• 1990’s-2000’s: Statistical studies concerning
algorithmic databasing of IMC, impressed toolmarks,
3d imaging, striated toolmarks, stochastic probability,
and more continue to be produced. Academia
begins to again become more involved due to the
prevalence of Forensic Science Programs at
universities.
Battlefield Forensics
• Firearm Identification is firmly lodged in wartime
battlefield forensic science and intelligence. Mobile
and temporary labs are staffed by USACIL (US Army
Criminal Investigation Laboratory) in the middle east
theatres, and USACIL has for 70 years intermittently
operated several Forensic Science Laboratories in the
US, the Phillippines, Japan, and Vietnam.
• In the first years of the Iraq/Afghanistan wars,
firearm and toolmark examiners were privately
offered upwards of $250,000 tax free to work one
year stints within the theatre of operations.
Identification Criteria
SWGGUN and AFTE
(Relevant Scientific Community)
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2.2
SWGGUN endorses the Association of Firearms and Tool Mark Examiners (AFTE) “Theory of
Identification” definition as set forth in the AFTE Journals (July 1992 Volume 24, Number 3
and Fall 2011 Vol. 43, No. 4) to be the generally accepted Criteria for Identification:
2.2.1
The theory of identification as it pertains to the comparison of toolmarks enables opinions of
common origin to be made when the unique surface contours of two toolmarks are in
“sufficient agreement.”
2.2.2
This “sufficient agreement” is related to the significant duplication of random toolmarks as
evidenced by the correspondence of a pattern or combination of patterns of surface
contours. Significance is determined by the comparative examination of two or more sets of
surface contour patterns comprised of individual peaks, ridges and furrows. Specifically, the
relative height or depth, width, curvature and spatial relationship of the individual peaks,
ridges and furrows within one set of surface contours are defined and compared to the
corresponding features in the second set of surface contours. Agreement is significant when
the agreement in individual characteristics exceeds the best agreement demonstrated
between toolmarks known to have been produced by different tools and is consistent with
agreement demonstrated by toolmarks known to have been produced by the same tool. The
statement that “sufficient agreement” exists between two toolmarks means that the
agreement of individual characteristics is of a quantity and quality that the likelihood another
tool could have made the mark is so remote as to be considered a practical impossibility.
2.2.3
Currently the interpretation of individualization/identification is subjective in nature, founded
on scientific principles and based on the examiner’s training and experience.
Random/Stochastic Process=
Chip Formation=
Microscopic Individuality!
Chip Formation-Chip Types
Tool Velocity and Chips
Chip Packing!
Pattern Matching
• One reason humans are such a successful species is
because we are so good at recognizing PATTERNS.
We recognize the faces of loved ones in crowds, we
remember faces instead of names. Look at Tetris,
child block games, Rubick’s cubes, the list goes on
and on.
• Firearm and Tool Mark Identification relies on
Pattern Matching.
• But—this type of pattern matching does not rely on
memory! It is performed in REAL TIME on a
comparison bridge microscope!
Comparison Bridge Microscope
Class Characteristics
• Class Characteristics are measureable features of a
specimen which indicate a restricted group source.
They result from design factors, and are therefore
determined prior to manufacture.
For Fired Bullets: Rifling twist, width, type
(conventional or polygonal), number of grooves.
For Fired Cartridge Cases: Shape of firing pin, shape of
firing pin aperture, ejector/extractor shape and
position, type of machining marks
(arched/linear/concentric), etc.
GLOCK Rectangular Firing Pin Aperture
Example of a Class Characteristic
Comparison Bridge Microscopic
Comparison between Two Cartridge
Cases fired in a Glock
GLOCK Pistol
Rifling Width Class Difference=Elimination
• Class Characteristics allow the informed expert to easily
ELIMINATE firearms as having fired unknown exemplars if the
class is different. We don’t hear about this too often in court
because when this is the case, the evidence usually is
exculpatory in nature and the investigation never makes it
that far.
• If the class characteristics produced by the tool or firearm are
similar, the expert should not eliminate the tool or firearm as
a possible source-even if the individual microscopic
characteristics are different. This is because surfaces can
wear and change over time, and can change extensively via
misuse or intentional abuse. Therefore, for instances where
known/unknown class characteristics are similar, the outcome
may be either inconclusive or an identification. Some outstate labs have a policy where they WILL eliminate based on
differences in individual characteristics. This is a point of
contention.
Subclass
• Subclass characteristics are discernible surface features of an
object which are more restrictive than Class Characteristics in
that they are produced incidental to manufacture, are
significant in that they relate to a smaller group source
(subset to the class that they belong), and can arise from a
source which changes over time.
• Subclass characteristics tend to be gross in nature (not fine or
minute).
• EXAMPLE: Smith & Wesson MIM firing pins
• Examiners learn about and publically share information
concerning subclass characteristics among units,
departments, and particularly through the AFTE Journal, the
AFTE Conference, and the AFTE Forums.
Individual Microscopic
Characteristics
• Allow for firearm and toolmark identification.
Absolutely random in nature (cannot be
predicted/from a stochastic process).
• Are created through chip formation, random
imperfections caused by chips caught within
working surfaces, differences in hardness of
steel, tool speed (ex. Drilling), accidental
imperfections from firing and handling/use,
and other mechanical means.
Lone Characteristic Within the FPI of Two Fired
Cartridge Cases
Lack of Significant Agreement
Between IMC on Two Fired
Cartridge Cases
Metal Injected Molding (MIM) Produces a
Subclass Mold Relic at the Break Line
These relics mimic individual characteristics, and while shared by a
unique subset of firing pins (pins made by a specific mold), it is a major
cause for concern.
First Step: Determining Tool Class Characteristics
Different Class!
TOOL MARK IDENTIFICATION
STRIATED IMPRESSION
Opposite Blade=More Agreement
VERY Similar Class (Hi-Point most likely).
NO Matching Individual Characteristics
One Group of Identified Cartridge Cases had
Reamer Chatter Marks that Resembled Fluting
Same Firearm, Consecutive Tests!!! Uh-oh!
FIREARMS IDENTIFICATION
STAMPED IMPRESSION
(Firing Pin Impression)
Another Firing Pin Identification
MSP Firearms Unit Facts
• All examiners are members of the Association of Firearm and Tool Mark
Examiners (AFTE)
• All examiners undertake, and must pass--a two year program consisting of
study and practical training. The program is modeled after the AFTE
training protocols. Two have been trained at the ATF-NFEA (National
Firearms Examiner Academy), which is a very prestigious program.
• Examiners are proficiency tested twice per year by an outside source.
• Examiners work in a laboratory that is accredited to ISO 17025 Standards
by ASCLD-LAB, and their units are audited on a yearly basis.
• “Measurements that Matter” utilize NIST calibrated equipment, traceable
to the BIPM (Bureau International des Poids et Measures).
• All examiners abide by two codes of ethics: The AFTE Code of Ethics and
the ASCLD Guide to Professional Responsibility.
– The former also requires two AFTE members who disagree to attempt
a constructive agreement prior to any testimony.
Choosing an Independent Expert
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If ethics are important to you (I hope so), is the independent expert a member in
good standing with AFTE?
Experience within an actual laboratory setting is important. Have you vetted the
independent expert? Do you know anyone in your state who can vouch for him or
her? Beware experts from other states who are not members of AFTE and have
limited track records. Do your homework!!
Remember that a presented “expert” may lack formalized training , may not be
proficiency tested (or may never have been), and may not utilize any type of
technical or peer review. Look for an expert who possesses these qualities.
There are many Independent Experts from around the country who fit the
qualities you might be looking for. They do work in civil and criminal cases. The
following list is a good place to start; they are all Distinguished Members of AFTE:
• http://www.afte.org/distmemberreferal.htm#midwest
Contacting an MSP Scientist
• Jim Piazza, Barry Wolf, Barney Whitesman, Pat Kirby, Lee
Sturtz, and other Mid-Michigan Defense Counsel have
personally contacted me prior to trial to discuss their cases.
• Only a handful of prosecutors in a 14 county service area
frequently contacted me prior to trial. Very few met with me
to go over the report findings and discuss significance/etc.
• There is nothing in our operations policy which precludes
talking with Defense Counsel about casework that has been
reported. My employees are friendly, dedicated, and
helpful…if you actually ask.
• Please don’t be a confrontational jerk if you contact my
employees outside of the courtroom context. You don’t need
to be.
Crafting Your Plan
• ASK the Forensic Scientist! If you are a defense counselor
worried about letting your cat out of the bag prior to trial, talk
to the expert shortly before the witness hits the stand. We
spend a lot of time waiting in the hallway.
• CALL or MEET with the Firearm Examiner if you can. Educate
yourself about the case. It is FREE.
• UNDERSTAND that the Examiner frequently knows much less
about the case particulars than you think. Typically, the only
cases where the examiner has investigative case knowledge of
any depth are those where the examiner worked the crime
scene. It can therefore be helpful to speak to the examiner to
discover fact-based opinions that could assist your
prosecution or your defense.
Asking the Right Questions
• Subjectivity-This is an Opinion, correct?
• Practical vs. Absolute Certainty-Explain
• Inconclusive Findings and the prevalence of firearms that
could have fired this bullet etc (Thousands/Hundreds of
Thousands/Millions??)
• Can you load and fire this bullet in another caliber cartridge
(i.e. a 115 grain 9mm Luger bullet in a .357 Magnum case)?
• Explore the Possibilities--How could this have happened/are
there other things that could account for this occurrence?
• Your testing can only place an object at a scene, not a person
at a scene, correct?
• www.firearmsid.com