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Thursday, May 31

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Morning Technical Session

Morning Moderator: Lansing Lee                                  Technical Session: Grand Ballroom A

8:00 AM


General Annoucements



AFTE 2007 Committee Member

8:05 AM


Stereoscopic 3D High Speed Video



Axel Manthei – Bavarian State Bureau of Investigation – Munich, Germany

Digital high speed cameras have become faster and faster in recent years. Two Shimadzu HPV 1 digital high speed cameras capable of 1,000.000 frames per second were available to the Kurzzeit company of Werner Mehl. This brought up the idea to produce stereoscopic 3D high speed videos of shotgun pellets and other projectiles in flight and upon impact on different material. Also the explosion of a revolver was captured in 3-D.

The digital high speed videos were produced with two simultaneously triggered Shimadzu high speed cameras. The illumination was achieved with special flashes. The complete triggering of the whole setup was done with a RTTS trigger system and a Kurzzeit chronograph. Both videos where merged with special software to produce anaglyph images to provide a stereoscopic 3D effect. This effect is commonly known from 3D movie theaters. For viewing the videos the typical 2 color glasses are necessary.

The goal to produce 3-D high speed videos of ballistic incidents was achieved. The critical task is to (at the right moment) trigger and synchronize both cameras and the flashes within up to 1/1.000.000 of a second. This was possible with the equipment.

The stereoscopic effect enables the viewer to get a 3 dimensional impression of the particle movement and the dispersion of fragments. The understanding of the high speed dynamics involved is improved.

8:20 AM


Validation Study: Impressed and Striated Breech Face Marks



Zachary Carr – Kansas Bureau of Investigation – Topeka, KS

The AFTE Glossary states that: “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.’” This study was designed and conducted in a way to test the long held theory that fired cartridge cases originating from different firearms vary sufficiently in individual characteristics to the point where incorrect identifications and incorrect eliminations occur at a very low rate. This study was designed as a validity test to be completed by fully trained firearms examiners on a wide scale, throughout the discipline, to obtain a large enough sample population to provide substantial results.

Twenty double blind sample sets were created to be sent to fully trained examiners across the United States. These sample sets consisted of a series of questions and knowns that originated from a pool of firearms. Isolated concentration on breech face marks was desired; to facilitate this, many parts that typically create identifying marks were kept constant. Great care was taken to anonymously send the sample sets to firearm examiners across the nation along with an equally anonymous method of reporting the conclusions. Each examiner was asked to record his/her results for the examination of each unknown in the sample set to include typical results of identification, elimination and inconclusive results when compared to the knowns; as well as inter-comparisons within the pool of unknowns when necessary.

To be determined before AFTE 2007.

To be determined before AFTE 2007.


8:45 AM


Assault Weapons and the Firearms Examiner



Richard Maruoka – Los Angeles Police Department – Los Angeles, CA

What happens when politics, the law, and forensic science mix? This is a relatively common occurrence, but when it involves firearms, the task of identifying specific types based on manufacturer, model, or even physical characteristics, the resulting outcome may be daunting for even the most experienced analyst.

This anecdotal paper will go into detail on the 18 year history of Assault Weapons Laws in the State of California, what it has attempted to regulate, issues it has raised, examples involving various types of firearms and devices, the impact it has on the Firearm Examiner, and what you may need to consider if your jurisdiction is planning to enact such legislation.


9:20 AM


BREAK – Held in the Vendor / Exhibitor Area – Grand Ballroom B & C



Sponsored by: AFTE 2007 Host Committee


9:50 AM






10:00 AM


How Much Can We Teach Microscopic Comparison in a Class Room?



Beta Tam – Los Angeles Police Department – Los Angeles, CA

Outline of Objectives

Give a general introduction to a more classroom orientated training approach for microscopic comparison.

Brief Methodology

  1. Development Stage – Discussions with trainees about identifications through the use of Drugfire images.
  2. Introductory Stage – Grouping the images together to form individual topics for classroom presentations. Examples of early classroom presentation include ad hoc power point presentation for manufacturing marks and variations in firing marks for trainees. Other materials include presentations of unusual case studies for technical meeting for working staff.
  3. Practical & Developing Stage – Put together the training materials available for the trainees and started the classroom training program with practical exercises. Development cycles started when trainee asked specific questions that needed to address and good examples from their training exercise.
  4. Testing of the system – The trainees’ confidence could only be built up through both practical exercises. The confidence of the trainer in the trainees built up through reviewing the ability of the trainees to solve their practical exercises.

Summary of Results
In order to ensure the competency of the trainee, we used the competency test normally used for testing the competency of newly employed experienced firearms examiner. Four out of the five students passed the competency test. We learned from the experience and modified the exercise requirements to avoid reoccurrences.

General Conclusions
The classroom approach yielded good result so far and the students could acquire more visual exposure to microscopic comparisons. It is more cost effective as most of the time only one full time trainer is required for the training program. When the full training materials are developed, it would be a comprehensive and systematic training program.


10: 40 AM


2007 SWGGUN Overview



Brandon N. Giroux – Federal Bureau of Investigation – Quantico, VA

Charles Clow – SW Institute of Forensic Sciences – Dallas, TX

This is an informational update on the Scientific Working Group for Firearms and Toolmarks. The presentation include a brief history of the working group, current Board Members, objectives, committees, and the documents/guidelines approved and available for peer review.

Upon completion of the Overview, a more detailed look will be taken at one of the most recent SWGGUN products.

The Scientific Working Group for Firearms & Toolmarks (SWGGUN) has produced an Admissibility Resource Kit that is designed to assist Firearm & Toolmark Examiners for admissibility hearings related to the science of Firearm & Toolmark Identification.

This overview will familiarize examiners with the content of the kit which includes:
  1. An Overview of the Admissibility Rules
  2. A Foundational Overview of Firearm & Toolmark Identification
  3. A Review of the Admissibility Elements
  4. Court Rulings
  5. Supporting and Opposing Viewpoints to Firearm & Toolmark Identification
  6. Appendices that include a Glossary of Terms, Online Resources and Visual Aids

Recently a Power Point Presentation based on the material within the resource kit was developed. This presentation can be adapted to an examiner’s specific needs and will be available for download under the Visual Aids section of the resource kit. This Power Point Presentation will be previewed.


11:20 AM


LUNCH (on your own)


  Afternoon Technical Session

Afternoon Moderator:  Eric Collins

12:50 PM



1:00 PM


The Statistical Significance of a Bullet Match



David G. Howitt – University of California, Department of Forensic Science – Davis, CA



Objectives: A derivation of the probability for finding patterns of matching lines, such as consecutive lines on the surfaces of a bullet has been made. The derivation assumes that the lines are derived from random processes and the criterion for correspondence is that both lines must fall within the width of the resolution limit imposed by the microscope. The expression can be used to determine the probabilities for any type of matching sequence and can therefore be used to quantitatively predict the probability that any specific match between two bullets can be associated with the same firearm.

Methodology: The number of different ways that a sequence of n lines can be distributed over the Q locations is given by an expression of the form W = Q!/n!.(Q-n)! . Given the number of random lines present on the surface of a land or groove impression this expression can be used to determine the total number of possible line sequences that they can form. The inverse of this being the likelihood that a particular sequence of lines will be found at random.

Results: The calculation of the probabilities for particular sequences of consecutive matching lines have been done and seem to match fairly well to the original data by Biasotti. According to this calculation if there are between 40 and 60 lines on the land impression the probability of a random matching doublet somewhere on the land surfaces of the bullet should be in the range from 0.23-0.45 and for a random triplet 0.006-0.011. For a match of five consecutive lines the likelihood is in the range from 1 in 50,000 to 1 in 83,000 and for six consecutive lines between 1 in 800,000 and 1 in 1.4 million.

Conclusions: It is possible to determine the probabilities for large numbers of consecutively matched lines on a bullet and to demonstrate that they are extremely unlikely to occur randomly. It is also possible to demonstrate the same sort of thing for any pattern of correspondence that extends over a distance greater than about a tenth of a millimeter on a land impression.


1:25 PM


A Comprehensive Statistical Analysis of Striated Tool Mark Examination

Michael Neel – BATFE Forensic Laboratory – Atlanta, GA



Objectives: The purpose of this paper is to quantify the difference between Known Matches (KM) and Known-Non Matches (KNM) and to determine if there is a statistically significant difference between the most conservative KM and the best observed KNM. This was done in an effort to assist examiners in their articulation of what constitutes a match and a known non-match.

Methodology: A variety of toolmark sources were utilized, including two-dimensional (2D) and three-dimensional (3D) toolmarks. In this research, over 4000 striated toolmark comparisons were examined for their Total Matching Lines (TML), Percent Matching Lines (%ML), and Consecutively Matching Striae (CMS).

Results: The microscopic comparisons were examined and tabulated to determine the probabilities of the observed CMS runs of various sizes. The statistical significance of the observations were determined using the Z-test.

Conclusions: Two dimensional and three dimensional Known Non-Matches (KNM) and Known Matches (KM) can be distinguished statistically even at the minimum criteria for identification as set forth by Biasotti and Murdock. There is a statistically significant difference between the CMS runs observed in the best KNM and the most conservative KM.



1:50 PM


Statistical Analysis of Toolmark Striations



Jeremy Craft – Iowa State University, Department of Statistics – Ames, IA



The objective of this study was to develop a statistical algorithm that would automatically and objectively compare quantitative data files obtained from toolmarks. The goal was to determine whether statistical validation could be given in support of toolmark examiner assertions, as a partial answer to questions raised by the Daubert decision.

Toolmarks were obtained from both sides of 50 sequentially manufactured screwdriver tips. The surface roughness of the toolmarks were measured using a stylus profilometer, producing a set of several thousand distinct data files. A computer program was developed using an internal verification and validation algorithm that employed a Mann-Whitney statistical analysis.

Results indicate that successful, non-ambiguous matching of two separate toolmarks is possible using the developed validation algorithm. Constraints on the association of a suspect tool to a particular toolmark require that test marks be made using the correct side of the tool and that the marks be made at similar angles.

These constraints are well known to toolmark examiners and have been known for many years. However, to our knowledge, this study presents the first totally quantitative, objective, statistical evidence in support of the expertise of toolmark examiners on this subject. As such it provides documentation as to the reliability and scientific nature of toolmark identifications.


2:15 PM


Decay Factor Tests for the Production of NIST SRM 2461 Standard Casings



John Song – National Institute of Standards and Technology – Gaithersburg, MD



Outline of Objects:
The electro-formation technique is used for duplicating surface specimens. A master specimen is put into a tank with electrolytes to produce a negative replica on the surface of the master. By repeating the same process on the negative replica, a positive replica is duplicated with the same surface topography as the master specimen. NIST plans to use this technique for the production of SRM (standard reference material) standard casings to support ballistics measurements nationwide. In order to ensure that the SRM casings are produced with virtually the same surface topography including casing signatures of firing pin, breech face and ejector mark, it is necessary to test the decay factor of the duplication process, and design an optimum plan for the duplication of a large amount of SRM casings with maximum uniformity of surface topography.

Brief Methodology:
Two decay factors, called horizontal and vertical decay factor α and β, are defined and tested for this purpose. The horizontal decay factor α is defined for quantifying topography decay among specimens duplicated one after the other from the same negative replica. The vertical decay factor β is defined for quantifying topography decay among specimens produced from one generation to the next generation.

Summary of Results:
26 replica casings are duplicated from the same master casing provided by the National Laboratory Center of the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). 17 casings are duplicated from the same negative replica, and are used for the tests of the horizontal decay factor α. Nine casings are the positive replicas of nine generations from the same master, and are used for the tests of the vertical decay factor β. The NIST topography measurement system is used for correlation measurements of surface topography. The topography differences are quantified by the cross-correlation function maximum CCFmax. Initial tests have shown that the electro-formation technique can duplicate replica casings with high fidelity of surface topography. Based on these tests, the horizontal and vertical decay factors are calculated as α = 0.016 % and β = 0.086 %.

General Conclusions:
Based on the horizontal and vertical decay factor, an optimum production plan is designed for the production of 256 SRM 2461 standard casings. It is expected that 256 SRM standard casings could be produced from the same master casing with CCFmax values higher than 95 %.


2:35 PM


7th Inning Stretch Break!




2:40 PM


Long Distance Shootings – A Case Example



Jan De Ceuster - Nationaal Instituut voor Criminalistiek en Criminologie – Belgium

A case example of how to approach a long distance shooting is presented. Care has to be taken to exclude any other possibility: direct shots and bullets falling from the sky.
To corroborate the long distance shooting, a number of clues and tools are given that will help to decide.

The results of a partial bullet trajectory reconstruction at the scene are used to simulate the complete bullet path with existing software EBV4 and Sierra's Infinity-5.
It is explained how this software can be applied to approach this problem and what useful information can be derived from this.

The bullet is examined with a microscope to look for any possible damage indicating a base first or tumbling bullet strike.

Corroborative test firings were executed, whenever necessary with downloaded ammunition, to examine the bullet's penetration/perforation capabilities. The bullet's velocity was tracked with a Weibel Doppler radar.

The bullet trajectory and degree of wounding were grounds to reject a direct shooting.

Bullet damage examination learned that it struck nose first, which is usually not expected for a bullet falling from the sky.

The trajectory reconstruction gave values for the angle of departure and downrange velocity. It was checked with test firings that the downrange velocity was still sufficient to explain the observed damage and wounding.

Conclusions: In presumed long distance shootings all possibilities should be checked to exclude direct shots and bullets falling from the sky:
  • What is the damage to the bullet and what is the damage to any intermediary objects and/or persons that were hit?
  • What are the required velocities for penetration / perforation of the given bullet / target combination?
  • Does the velocity drop while perforating a target changes at a lower downrange velocity?

The software that was used for the trajectory reconstruction gave a good indication for angle of departure and range. Between the 2 programs there is a minor difference in downrange velocities. The ballistic coefficient should be chosen with care as it has an important influence on the trajectory.


3:00 PM


Assessment of Comparison Macroscope Optical Resolution Based on Instrument Age



Wayne Buttermore – Leica Microsystems – Bannockburn, IL

  Objective: To determine the resolution capabilities of current microscope technology as compared to earlier produced comparison macroscope systems. Correlation to the theoretical limits as defined by calculated values are compared to observable resolution.

Method: Seventeen trained operators used a certified resolution test slide with reproducible illumination and magnifications, to determine the resolving capabilities on 16 different comparison macroscopes systems ranging in age from less than 12 months to more than 30 years old.

Summary of Results: New Microscopes out performed older systems consistently, however, it does not prove that older microscopes are not capable of resolving structures that are typical of firearms and toolmark examinations:

General Conclusions: A variety of factors lead to the ability of a microscope system to resolve structures, including illumination, filtering, gender, age of the instrument, instrument maintenance, color of light, and visual acuity of the operator.


3:25 PM


17 and 22 Caliber Cartridge Interchangeability



Justin Rankin – Kansas Bureau of Investigation – Kansas City, KS

Objectives: (1) To determine the cartridge interchangeability between the 17 and 22 caliber families. (2) To study the effect of this interchangeability on physical and individual characteristics exhibited on fired bullets.

Methodology: Utilizing a Ruger Single Six revolver, test fires were obtained from combinations of 17 and 22 caliber cylinders/barrels. Various bullet materials were used in the test firing process. Microscopic examination was performed on the test fired bullets to determine if physical and/or individual characteristics were exhibited.

Results: The different 17 and 22 caliber cylinder/barrel combinations showed definite physical characteristics including increased length, decreased diameter, and unusual deformation in some cases.

Conclusions: (1) It is possible to fire 22 caliber bullets from a 17 caliber chambered cylinder and barrel with no modification to the firearm.
  • 22 Short caliber cartridges can be loaded and fired in a cylinder chambered in 17
    Mach 2.
  • 22 Long Rifle caliber cartridges can be loaded and fired in a cylinder chambered for 17 HMR.

(2) The unique physical characteristics exhibited by the test fired bullets obtained from the cylinder / barrel combinations have the potential to aid examiners in the event that similar items are received in case work.


3:50 PM


Micro-Marked Firing Pins: Character Durability and Micro-Marked Legibility



Michael Beddow - University of California, Department of Forensic Science – Davis, CA

  The laser machining of microscopic encoding structures on specific firearm components has been proposed to assist in the identification of expended ammunition components found at crime scenes. Since the release of the first generation of this technology significant advances in the laser machining technology and in the encoding structures have been made. This study involved the testing of second generation firing pins produced by ID Dynamics, LLC. Second generation micro-marked firing pins contain three different forms of encoding: alphanumeric, gear and radial bar codes. The durability of these micro characters and legibility of their impressions were observed by the testing of eleven semi-automatic pistols, two semi-automatic rifles and a pump action shotgun on a variety of different ammunition brands. All cartridge cases were analyzed using a stereo zoom microscope equipped with a ring light and polarizing filter, and all firing pins were analyzed utilizing a Philips XL30 Scanning Electron Microscope.

The alphanumeric and gear code structures showed minimal signs of degradation with repeated test firing beyond 1000 rounds; however specific instances of degradation were noted. Eight of the eleven semi-automatic pistols tested showed severe degradation of the radial bar code structures. This degradation was caused by the continual contact between the sides of the firing pins and the firing pin aperture. This contact obliterated a section of the radial bar code structures. The applicability of the codes other than the alphanumeric could not be evaluated because decoding information was not available. This study suggests that the placement of an eight digit alphanumeric code on the face of the firing pin is the most durable. Any increase in the number of digits in this code would reduce the legibility of the impressions.

The legibility of the impressions produced by these micro-marked firing pins varied between firearms. Transfer rates were observed from zero to 100% for all encoding formats. All of the semi-automatic pistols and one semi-automatic rifle showed a minimal decrease in the legibility of the impressed characters with continued test firing. Three major factors affected the legibility of the impressed characters for each of the firearms tested: ammunition brand, firing pin drag, and multiple strikes of the firing pin within the same impression (all firearms tested did not produce firing pin drag and multiple firing pin strikes). The legibility of the impressed characters was directly dependent upon the brand of ammunition tested. This ammunition brand dependence was confirmed upon repeated test firing of each brand of ammunition. One semi-automatic rifle and the pump action shotgun showed a decreasing trend in impression legibility throughout test firing. This decrease in transfer rate was correlated with the degradation of the encoding structures on these two firing pins. This technology is currently not suitable for .22 caliber rimfire firearms.

At the present time this technology is feasible, but is not applicable to all firearms. Further research and development needs to be completed prior to the widespread commercial implementation of this technology.


4:05 PM



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