FBI GSR Symposium - QuoData · PDF fileFORENSIC SCIENCE COMMUNICATIONS ... 6/7/2006 Michael A....

6/7/2006Michael A. Trimpe - Hamilton County Coroner's Lab 1

FBI GSR Symposium

Michael A. Trimpe


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


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


FORENSIC SCIENCECOMMUNICATIONS

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GSR Defined

• Best description is “gunshot residue (GSR)”

• Best classification “characteristic” not “unique”


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).


GSR Defined

• Pb,Ba,Sb spheroid particle can be described as having come from a discharged firearm

• Majority report two component particles


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


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


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.


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


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


• 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


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


• “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


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


Testing of Victims & Suspected Testing of Victims & Suspected SuicidesSuicides


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


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).”


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


“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 “


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


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”


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


Technical Review

• “The majority of attendees indicated that their laboratories require that all GSR reports are peer reviewed”


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


Methodology

• the symposium attendees conduct GSR analyses using SEM/EDS

• Manual confirmation of a representative sample should always accompany automated searches


ASTM Guidelines

• A representative from ASTM was present at the symposium

• Comments and suggestions were noted for later discussion within the committee.


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


FORENSIC SCIENCECOMMUNICATIONS

Go to: www.fbi.gov/hq/lab/fsc/current/index.htm

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