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6/7/2006Michael A. Trimpe - Hamilton County Coroner's Lab 1
FBI GSR Symposium
Michael A. Trimpe
6/7/2006Michael A. Trimpe - Hamilton County Coroner's Lab 2
A short time ago, in a town far, far away…
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Contamination issues – possible false positivesA) brake pads
FBI Symposium TableLuftl - brake padsMcVicar - Motorcycle brake pad GSR studySkip Schwoeble - brake tiff 1Skip Schwoeble - brake tiff 2Skip Schwoeble - explanation of testsGiacalone - BrakesGiacalone - fireworks and brake pads
19. Based on current studies it is possible to differentiate between brake pad particles and gunshot residue particles.
a) agreeb) disagreec) need to discuss
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19. Based on current studies it is possible to differentiate between brake pad particles and gunshot residue particles.
a) agreeb) disagreec) need to discuss
20. Based on current studies it is possible to differentiate between brake pad particles and gunshot residue particles when taking into consideration the entire population and morphology.
a) agreeb) disagreec) I don’t know
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FORENSIC SCIENCECOMMUNICATIONS
Go to: www.fbi.gov/hq/lab/fsc/current/index.htm
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GSR Defined
• Best description is “gunshot residue (GSR)”
• Best classification “characteristic” not “unique”
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Torre C, Mattutino G, Vasino V and Robin C “Brake Linings: A source of Non-GSR particles containing Lead, Barium and Antimony,” Journal of Forensic Sciences, Vol. 47,No.3, 2002 pp. 502.
Fig. 6- “Clean” Pb-Sb-Ba-particle. Sample taken from the front rim of a car (Volkswagan).
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GSR Defined
• Pb,Ba,Sb spheroid particle can be described as having come from a discharged firearm
• Majority report two component particles
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Composition and Morphology
• To categorize particles as GSR consider:– Morphology – signs of rapid solidification
– Elemental Composition – among the population
• And if necessary:
– Comparison to Known – ammunition in case
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BRAKE PADS
134,000 brake dust particles analyzed Few Ba,Sb,Fe NO Pb,Ba,Sb
66 vehicles –8 VW 2 Audi
DeGaetano et.al
4 Ba,Sb but not correct morphology11 car brakesR. White
Can find Pb,Ba,Sb containing material, but the inclusion of other particles and the morphology make GSR unique
Brake padsGiacalone
RESULTSTESTED
All potential GSR particles contained Mg-Si-Fe constituents
20 VW brake discs
Schwoeble
Small levels of Pb, Sb, and Ba, but not fused together
11 Motorcycle brake discs
Gerard -McVicar
Small amount of GSR-like particles, (with molten looking shape), which lacked Ba
BMW brakesLuftl & Gebhart
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Hand Sampling and Contamination
• Sampling should be done:
• At the scene, expeditiously, before bagging, & before being placed in police vehicle
A police officer’s hands could be a source of GSR.
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POLICE CARS
Only 2 Pb,Ba,Sb particles were found82 police carsBerk
3 cars had Pb, 2 cars had Pb/Sb, no cars had Pb/Sb/Ba or Pb/Ba
40 samples from backseats of 20 police cars
Springer
14 had Pb,Ba,Sb; 5 had 2-components 7 had no particles
Backseats of 26 police carsCrowe and Rugh
After 10 minutes, 4 of the 41 had Pb,Ba,Sb particles on their hands
41 hand samples from clean individuals, handcuffed and placed in backseat
45 had consistent GSR particles, 4 of those had Pb,Ba, Sb particles
50 of 205 samples collected from the backseat of patrol cars
Kowal
RESULTSTESTED
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Police Hands
16 had PbSb or PbBa none had Pb,Ba,Sb
100 handcuffed subjectsMartinez & Garcia
30% had PbSb and/or PbSbBa particles
43 non-shooting police officers
Martinez
24 had Ba,Sb or Pb,Ba,Sb particles on their hands, clothing, or equipment
30 non-shooting police officers
McVicar
RESULTSTESTED
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• The avg. person does not have GSR on his hands
• GSR can transfer from one surface to another
• Bystanders at a shooting can test + for GSR
• Monitoring of work environment should be included in GSR protocol (31 do it now)
Hand Sampling and Contamination
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IN-HOUSE STUDIES
GSR particles found in shooting range, in work and administration areas, and in the air vents. None found in SEM or Trace rooms.
Firearms SectionMartinez
Small GSR particles were consistently found in areas associated with shooting or fired weapons in contrast to negative findings in reference areas
Samples taken over 7 years in various areas, such as car, SEM room, at the range, and on person
Lebiedzik
Keep samples separate, use barriers, periodic cleaning of the lab
LaboratoriesNiemeyer
Continual airborne particle collection, analyzed monthly, is sufficient to monitor for contamination
Areas where GSR particles are examined
McVicar
The second cloth had approximately 27% of the GSR particles as the first
Piece of cloth shot with .38 caliber revolver, second piece of cloth rubbed on the first
White
RESULTSTESTED
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• “It is appropriate for a lab to have acceptance criteria…the analyst should have the discretion to prioritize samples submitted and discontinue analysis when GSR is found.”
Case Acceptance Criteria
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ACCEPTANCE CRITERIA
Trained officer should collect samples within 8 hours.
No victims, no one who washed hands or was in contact with GSR in any other way. No heavily contaminated samples. No shoes. No taped samples.
McVicar
Sample only suspects hands, not exceeding 8 hours.
No victims, no one possessing a firearm, no one who washed hands
FDLE (kits)
Collect within 4-6 hours suggested
Of 286 face samples, GSR was found in 9 cases where it was not on hands – discontinued face sample in kits
Fibrous cloth - Problems with charging and concealment
DeGaetano
No victims, collect within 4-5 hours suggestedTrimpe
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Testing of Victims & Suspected Testing of Victims & Suspected SuicidesSuicides
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SUICIDES
80% positive
94% positive
118 homicide victims
166 suicide victims
Crowe
62% positive 10% had 1 GSR particle
126 Suicide cases, from various types of firearms
Martinez
79% positive80 suicide casesTrimpe
87% positiveSuicides (2040 cases) = 39% of GSR cases
DeGaetano
RESULTSTESTED
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Testing of ClothingPersistence on clothing is expected to be longer than on skin, so the time of deposition cannot be determined.
“…there are circumstances when items of clothing associated with a subject and event should be examined for the presence of GSR (e.g. when hand samples are negative or not available).”
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Testing of Clothing Suggestions:
• Trained personnel sample clothing while worn by subject
• Use lifter stubs not vacuum
• Use paper not plastic for packaging
• Dedicate SEM to one case when sample is loaded with fibers
• Carbon coat samples as needed
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“Instant Shooter” Identification Kits
• “GSR lifts for SEM should always be taken before the instant shooter swabbing is employed.”
• “the majority of the group did not think that these kits should be used to collect or test for GSR in place of SEM/EDS analysis and most were not willing to analyze them “
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Significance and Report Writing
• most experts felt that even one PbBaSb spheroid particle is enough for a “positive” result.
• GSR cannot be attributed to a particular event
• GSR cannot be used to distinguish between shooters and bystanders
• Absence of GSR does not preclude the possibility of that individual having discharged a firearm
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Significance and Report Writing
• Majority contend a qualifying statement is necessary:
Finding GSR on a person’s hands is “consistent with that person having fired a weapon, having been in the vicinity of a fired weapon, or having touched an item with gunshot residue on it”
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Distance and Direction of Particle Travel
GSR particles were found on all 3 bystanders, but to a lesser degree than the shooter
Bystanders within 1 meter of shooter, various weapons used
McVicar
Majority of GSR particles found in front of muzzle and on shooter’s hands, few particles recovered beyond 15 feet
GSR distribution of known firearms in a closed environment
Springer
The individuals all had GSR particles on them, the gloves 19 ft away contained GSR particles
Gloves left in room at various distances and individuals walking through room
White and Mershon
RESULTSTESTED
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Technical Review
• “The majority of attendees indicated that their laboratories require that all GSR reports are peer reviewed”
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Proficiency Testing
• the symposium participants all agreed, the European Network of Forensic Science Institutes (ENFSI) GSR proficiency test should be adopted as an approved test for GSR analysis by SEM/EDS
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Methodology
• the symposium attendees conduct GSR analyses using SEM/EDS
• Manual confirmation of a representative sample should always accompany automated searches
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ASTM Guidelines
• A representative from ASTM was present at the symposium
• Comments and suggestions were noted for later discussion within the committee.
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Areas without agreement• What to call 2-component particles
• Are Ba,Sb particles given same weight as Pb,Ba,Sb
• How to describe morphology
• To search for sub-micron particles
• Do you QA collection kits?
• Require completed submission sheets
• To use one stub for both hands
• Cut off time between shooting and collection – 4, 5, 6, 8, 12+ hours
• Body of report = instrument, particles, quantity, & conclusion
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FORENSIC SCIENCECOMMUNICATIONS
Go to: www.fbi.gov/hq/lab/fsc/current/index.htm