ASTM E3284-23

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E3284 − 23
Standard Practice for
Training in the Forensic Examination of Primer Gunshot
Residue (pGSR) Using Scanning Electron Microscopy/
Energy Dispersive X-Ray Spectrometry (SEM/EDS)
This standard is issued under the fixed designation E3284; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Continuing Education, and Professional Development
Programs
1.1 This practice describes the minimum requirements of a
E3309 Guide for Reporting of Forensic Primer Gunshot
training program in primer gunshot residue (pGSR) analysis by
Residue (pGSR) Analysis by Scanning Electron
scanning electron microscopy/energy dispersive X-ray spec-
Microscopy/Energy Dispersive X-Ray Spectrometry
troscopy (SEM/EDS). It describes lessons, practical exercises,
(SEM/EDS)
and progress monitoring and evaluation that should be part of
2.2 Other Documents:
a laboratory’s training program.
SWGGSR Guide for Primer Gunshot Residue Analysis by
1.2 The primary purpose of this practice is to facilitate the
Scanning Electron Microscopy/Energy Dispersive X-Ray
development and implementation of training programs in crime
Spectrometry
laboratories or other such analytical entities that participate in
the detection, analysis, and classification of pGSR particles.
3. Terminology
1.3 This standard does not purport to address all of the
3.1 Refer to Practice E1588, Terminology E1732, and
safety concerns, if any, associated with its use. It is the
Practice E2917 for terms relative to this practice.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
4. Summary of Practice
mine the applicability of regulatory limitations prior to use.
4.1 This practice provides a summary of the knowledge and
1.4 This international standard was developed in accor-
skills required to establish competency as an independent
dance with internationally recognized principles on standard-
pGSR analyst.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 4.2 The following topics related to the forensic examination
mendations issued by the World Trade Organization Technical of pGSR using SEM/EDS are included:
4.2.1 Occurrence, transfer, and persistence of pGSR;
Barriers to Trade (TBT) Committee.
4.2.2 Contamination minimization and the prevention of
2. Referenced Documents
loss of trace evidence;
4.2.3 Other forms of trace evidence [such as deoxyribo-
2.1 ASTM Standards:
nucleic acid (DNA) and fibers] that could be associated with
E620 Practice for Reporting Opinions of Scientific or Tech-
persons or exhibits that require sampling for pGSR;
nical Experts
4.2.4 Evidence recovery methods;
E1588 Practice for Gunshot Residue Analysis by Scanning
4.2.5 Evidence handling procedures;
Electron Microscopy/Energy Dispersive X-Ray Spectrom-
4.2.6 Evidence packaging and documentation;
etry
4.2.7 Use and maintenance of SEM/EDS and auxiliary
E1732 Terminology Relating to Forensic Science
equipment;
E2917 Practice for Forensic Science Practitioner Training,
4.2.8 Quality assurance procedures;
4.2.9 The analysis of pGSR using SEM/EDS and other
techniques that have been/can be used to analyze GSR;
This practice is under the jurisdiction of ASTM Committee E30 on Forensic
Sciences and is the direct responsibility of Subcommittee E30.01 on Criminalistics.
4.2.10 The formation of pGSR and other forms of GSR,
Current edition approved Oct. 1, 2023. Published October 2023. DOI: 10.1520/
such as organic GSR;
E3284-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from Scientific Working Group for Gunshot Residue (SWGGSR),
the ASTM website. https://www.swggsr.org/.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E3284 − 23
4.2.11 Identification and classification of pGSR; 6.1.3.1 Practical exercises; and
4.2.12 The demonstrated ability to differentiate between 6.1.3.2 Assisting in and performing supervised casework.
pGSR and non-firearm, pGSR-like particles;
6.1.4 Examinations and tests:
4.2.13 Interpretation of results of pGSR analysis and limi-
6.1.4.1 Written and oral tests;
tations of interpretation;
6.1.4.2 Practical laboratory tests; and
4.2.14 Preparation of scientific reports for potential inclu-
6.1.4.3 Mock/moot court.
sion as court evidence; and
6.2 This is an extensive training program and it is expected
4.2.15 Presentation of expert opinion evidence pertaining to
that an inexperienced examiner would take approximately six
pGSR in court.
months to one year to complete.
4.3 This practice describes lessons, practical exercises, and
6.2.1 For the purpose of this practice, an inexperienced
methods of progress monitoring and trainee evaluation de-
examiner is an individual who has little knowledge in trace
signed to be incorporated into an individual laboratory’s
evidence, minimal knowledge of SEM or EDS, or minimal
training program. Topics for discussion occur between the
knowledge of pGSR evidence.
trainee and the trainer.
6.2.2 Portions of this training program can be substituted or
removed based on demonstration of the trainee’s previous
5. Significance and Use
knowledge and experience of the theory or instrumentation
5.1 This practice is intended to be used by subject matter
related to this type of analysis.
experts in the field of forensic pGSR analysis who have met
their laboratory’s technical requirements to be assigned to the
7. Records of Training
role of trainer in the category of testing that deals with the
7.1 Document and maintain all training records in accor-
detection, analysis, and classification of pGSR particles.
dance with Practice E2917.
5.2 This practice is intended to be used in conjunction with
Practice E2917, as well as the laboratory’s existing generalized
8. Responsibilities
training protocols, standard operating procedures, and quality
practices, to develop a complete training-to-competency pro- 8.1 The training coordinator, who has technical competency
gram in pGSR analysis by SEM/EDS. This practice provides in all aspects of the forensic discipline of pGSR examination,
the required additional, discipline-specific elements for pGSR and supervises the administration of the training program. The
analysis by SEM/EDS, in accordance with 5.3.2 of Practice training coordinator can also function as a trainer.
E2917; it does not include the core specific elements covered
8.2 Responsibilities of the trainer(s) include:
in 5.3.1 of Practice E2917.
8.2.1 Introduction to the relevant scientific literature, labo-
5.3 The topics and procedures outlined in this practice are
ratory and technical procedures, training material, and appro-
grounded in the body of scientific literature that exists in the
priate reference collections;
field of pGSR examination.
8.2.2 Instruction in the laboratory evidence management
5.3.1 Additional sources of information on pGSR
systems;
examination, not specifically mentioned in this document,
8.2.3 Instruction in the documentation of casework;
should be considered, added, or substituted. A review of new
8.2.4 Instruction in and discussion of the relevant scientific
sources of information on general forensic methods and pGSR
literature and theory pertaining to SEM/EDS and pGSR;
examinations should be carried out on a regular basis (e.g.
8.2.5 Instruction, guidance, and supervision of practical
annually or biannually) to incorporate well-established current
skills pertaining to:
findings and methods into the training program and to replace
8.2.5.1 Contamination minimization and the prevention of
any outdated methods.
loss of trace evidence;
5.3.2 When possible, make additional training available to
8.2.5.2 Evidence recovery methods;
the trainee. Such training might include off-site short courses,
8.2.5.3 Evidence handling procedures;
short internships, and specialized training by experienced
8.2.5.4 Evidence packaging and documentation;
examiners.
8.2.5.5 Use and maintenance of SEM/EDS and auxiliary
6. Guidelines equipment;
8.2.5.6 Quality assurance procedures;
6.1 Training guidelines provide the trainee with the required
8.2.5.7 The analysis of pGSR using SEM/EDS and its
theoretical knowledge and practical skills in pGSR
limitations;
examination, analysis, and interpretation through a combina-
8.2.5.8 Other techniques that have been/can be used to
tion of the following training methods:
analyze GSR;
6.1.1 Reading of relevant literature;
8.2.5.9 The formation, identification, and classification of
6.1.2 Instruction by and observation of pGSR examiners:
pGSR and other forms of GSR;
6.1.2.1 and discussions;
8.2.5.10 Interpretation of results, including limitations of
6.1.2.2 Demonstration of skills;
the method and limitations of activity-level inferences;
6.1.2.3 Observation of case work; and
6.1.2.4 Observation of expert court testimony. 8.2.5.11 Preparation of scientific reports for potential inclu-
6.1.3 Supervised practice of skills: sion as court evidence; and
E3284 − 23
8.2.5.12 Presentation of expert opinion evidence pertaining 8.4.10 Demonstrating competency in supervised casework.
to pGSR in court, including the specific legal issues as
9. Human Factors
described in E2917.
8.2.6 Establishing pass criteria for, designing, reviewing
9.1 Core specific elements of human factors as described in
results of, and documenting:
E2917.
8.2.6.1 Oral and written assignments or tests or both. These
9.2 Awareness of human factor issues as related to exami-
tests are administered along with practical laboratory tests as a
nation of GSR, including the following:
means of determining the trainee’s comprehension of the
9.2.1 Cognitive factors that influence forensic decision
material and to document the training. Design questions to test
making, including cognitive bias and task-relevant versus
the trainee’s theoretical and practical knowledge.
task-irrelevant contextual information.
8.2.6.2 Practical exercises to allow the trainee to learn and
9.2.2 Ways to minimize the impact of cognitive bias on the
practice the skills needed to perform casework. Review the
forensic decisionmaking process, including separation of
trainee’s performance during the exercises to evaluate the
duties, specification of decision criteria, linear sequential
trainee’s ability to conduct pGSR examinations.
unmasking, documentation for the basis of decisions, and
8.2.6.3 Simulated casework to demonstrate understanding
blinding.
of the various aspects of casework including: record keeping;
9.3 Reading Assignments—See Refs 1-5.
processing of evidence; sample preparation; SEM/EDS analy-
sis of prepared samples; and identification, classification, and
10. Introduction to pGSR Evidence
interpretation of pGSR evidence.
10.1 Include the following:
8.2.6.4 Comprehensive competency test(s) before the
10.1.1 Types of GSR:
trainee analyzes pGSR cases independently. Design compe-
10.1.1.1 Organic GSR; and
tency test(s) to mimic the challenges encountered in actual
10.1.1.2 Inorganic GSR, including pGSR.
casework, requiring the trainee to demonstrate knowledge of
10.1.2 Concepts and techniques of particle analysis relevant
the laboratory’s procedures in handling evidence, taking notes,
to pGSR by SEM/EDS.
maintaining chain of custody, and writing a report, as well as
the analytical complexities encountered during examination of
10.2 Reading Assignments—See Refs 6-11.
pGSR evidence.
8.2.6.5 Supervised case work.
11. pGSR Formation
8.3 The trainer monitors the trainee’s progress to ensure 11.1 Include the following:
thoroughness and completeness, and evaluates the progress 11.1.1 Basic primer composition;
according to objective criteria established by the laboratory. 11.1.2 The physical processes involved in the initiation of
the primer;
8.3.1 Conduct periodic progress assessments.
8.3.2 Address deficiencies in the trainee’s performance and 11.1.3 The chemical and physical processes that lead to the
formation of pGSR particles;
remediate through additional training or a reevaluation of the
training program, as necessary. 11.1.4 Particle morphologies;
11.1.5 Different types of firearms and how they vary in the
8.3.3 Continued deficiencies in the trainee’s performance
suggest the unsuitability of the trainee for casework in this emission of pGSR;
11.1.6 Factors affecting the deposition and distribution of
area.
pGSR and the extent of limits on what is known about each of
8.4 Responsibilities of the trainee include:
these factors:
8.4.1 Self-study of reading materials;
11.1.6.1 The shooter;
8.4.2 Demonstrating competence in the application of the
11.1.6.2 The victim of a gunshot;
practical skills covered by the training program;
11.1.6.3 Persons or items in the proximity of a firearm
8.4.3 Successful completion of practical exercises;
discharge; and
8.4.4 Successful completion of written or oral tests or both;
11.1.6.4 The environment in which a firearm is discharged.
8.4.5 Observation of and assisting in casework being con-
11.2 Reading Assignments—See Refs 12 and 13.
ducted by an experienced examiner;
8.4.6 Observation of court testimony given by an experi-
12. Firearms/Ammunition
enced examiner or reviewing transcripts in which pGSR
evidence was presented or both;
12.1 Include the following:
8.4.7 Conducting themselves in an ethical and professional 12.1.1 Different types of firearms and their mechanisms;
manner; 12.1.2 Basic components of ammunition and their purpose
8.4.8 Participating in the quality assurance and quality and function, and how the chemical composition of how each
control program of the laboratory and, particularly, pertaining contributes to pGSR:
to pGSR examinations, sampling and analysis using SEM- 12.1.2.1 Bullet/projectile;
EDS; 12.1.2.2 Cartridge case;
8.4.9 Successful completion of competency tests in the 12.1.2.3 Propellant; and
detection of pGSR and subsequent interpretation and reporting 12.1.2.4 Primer.
of pGSR results; and 12.1.3 Various types of primers, including, at a minimum:
E3284 − 23
12.1.3.1 Sinoxid; 15.1.4 The potential for contamination and/or loss or de-
12.1.3.2 Rimfire; and struction of other forms of trace evidence that could be
12.1.3.3 Lead free primer and heavy metal free (HMF) associated with persons, clothing, or inanimate objects from
primer. which sampling for pGSR is required and the possible impact
12.1.4 Typical primer components, their elemental compo- on co-processing and sequential processing efforts for evidence
sition and their purpose: such as DNA, fingerprints, and fibers.
12.1.4.1 Shock-sensitive explosives or initiators;
15.1.5 Procedures that can be used to minimize
12.1.4.2 Sensitizers; contamination, loss, or destruction of other forms of trace
12.1.4.3 Oxidizers;
evidence when examining and sampling from persons,
12.1.4.4 Fuels; and clothing, or inanimate objects from which sampling for pGSR
12.1.4.5 Frictionators.
is required and capability to apply these procedures, if appli-
cable.
12.2 Reading Assignments—See Refs 14-18.
15.1.6 Procedures for documenting detected contamination
13. Retention and Transfer
and how the contamination was addressed.
13.1 Include the following:
15.2 Reading Assignments—See Refs 28-30.
13.1.1 Factors that can affect the retention, redistribution, or
loss of pGSR particles and the extent of limits on what is
16. Instrumentation and Analysis
known about each of these factors including:
16.1 SEM/EDS:
13.1.1.1 The time since discharge;
16.1.1 Evaluate the trainee’s ability to optimize SEM per-
13.1.1.2 The physical characteristics of the surface on
formance and SEM/EDS detection parameters for the auto-
which the pGSR particles have deposited;
mated analysis and detection of pGSR. Include the following,
13.1.1.3 The activity that the surface has been exposed to
where applicable:
since discharge such as vigorous physical activity, washing, or
16.1.1.1 SEM electron gun filament saturation and filament
exposure to the environment;
replacement, where applicable;
13.1.1.4 Transfer of pGSR particles subsequent to the initial
16.1.1.2 SEM column alignment;
deposition from the discharge of a firearm; and
16.1.1.3 Understanding of SEM/EDS parameters for opti-
13.1.1.5 pGSR particles may remain for many years on or
mum imaging resolution to include accelerating voltage, beam
inside an object if that object remains undisturbed.
current, condenser lens (CL) aperture selection (if so
13.2 Reading Assignments—See Refs 19-22.
equipped), and final aperture (if interchangeable);
14. Collection of pGSR Samples 16.1.1.4 Knowledge of the current particle classification
scheme in the manufacturer’s EDS software for identifying
14.1 Include the following:
detected particles;
14.1.1 The various types of collection media including
16.1.1.5 Modification or addition of particle classes to the
adhesive lifters, swabs, and vacuum filtration and their advan-
particle classification scheme, if allowed by the software;
tages and disadvantages.
16.1.1.6 Set up and optimization of SEM imaging;
14.1.2 Presumptive field test kits for GSR, their limitations,
16.1.1.7 Setting of stage positions to define the locations
advantages, and disadvantages.
and analysis regions for any standards, reference materials, and
14.1.3 Impact of sampling environment, including the pres-
the case specimen samples;
ence of moisture, blood, and soil on the collection of pGSR
particles. 16.1.1.8 Set up of automated analysis run with appropriate
reference materials to ensure t
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