Primer Gunshot ResiduePrimer Gunshot Residue(P(P--GSR) on Random PopulationGSR) on Random Population

Michael V. Martinez, MSFSTechnical Leader-Forensic Scientist

Bexar County Criminal Investigation Laboratory San Antonio, Texas

FORENSIC SCIENCE CENTERFORENSIC SCIENCE CENTER

Special Thanks To:Special Thanks To:

Timothy C. FallonTimothy C. FallonCriminal Investigation Laboratory DirectorCriminal Investigation Laboratory Director

OpinionOpinion

! Many Papers and Attorneys Focus Attention on the Abstract Possibilities of Finding P-GSR Particles Regardless of Likelihood

! The Constant Search for False Positives! More Weight is Given to Indeterminate

Results as being Negative for Discharging a Weapon

Questions Asked by AttorneysQuestions Asked by Attorneys

! What is P-GSR?! Where Did it Come From?! Significance of Finding P-GSR or Not Finding

P-GSR?! Prevalence in Population?! What is the Radius of P-GSR from a

Discharged Weapon?! How About Secondary, Tertiary of Quaternary

Transfer of P-GSR?! Contamination Possibilities?! Can Aerosolized P-GSR be Carried by Wind?

StudiesStudies

! Conducted Studies to Address some of the Questions Asked by Attorneys:– Environmental/Occupational Study– Magistrate Study– Suicide Study– Contamination Study

Gunshot Residues (GSR)Gunshot Residues (GSR)

! Burned, Partially Burned and Un-Burned Gunpowder

! Metallic Particles from Bullet, Barrel, and Casing

! Primer Ingredients are Generally: Lead Styphnate, Barium Nitrate and Antimony Sulfide.

! Soot, Bullet wipe, Stippling

Primer Gunshot Residue (PPrimer Gunshot Residue (P--GSR)GSR)

! Microscopic P-GSR particles condense in cooler ambient air.

! Particles drop onto persons and objects in vicinity of weapon discharge.

Primer Gunshot Residue (PPrimer Gunshot Residue (P--GSR)GSR)

! A Metal Alloy of Lead, Barium and Antimony Particles

! Found on objects that are in contact with and in close proximity to a discharged firearm, (includes firing a weapon)

Primer cap/cup components from small arms known asPercussion primers-(first introduced by reverend Alexander

forsyth in 1805)

The United States & Canada use a Boxer design primer cap, which has an internal anvil that is inserted into the primer cup.

European countries use a Berdan design type of primer cap that lacks an integral anvil.

Small arms primers consist of an explosive, an oxidizer, a fuel and a frictionator.

Other components act as sensitizers and binders.

Explosives- Fulminates, Lead or Silver Azide, Lead Styphnate, Mercury Fulminate, TNT and others.

Oxidizers- Barium Nitrate, Lead Nitrate, Lead Dioxide, Potassium Chloride.

Fuels- Antimony Sulfide and Calcium Silicide (which also acts as a Frictionator), Nitrocellulose, Carbon Black, Lead Thiocyanate, Gum Arabic (which also acts as a binding agent), Powdered metals such as Aluminum, Magnesium, Zirconium or their alloys.

Frictionators- Ground Glass and Aluminum powders which also acts as a fuel.

Sensitizers- Tetracene, TNT, PETN.Binders- Gum Arabic, gum tragacanth, Glue, Dextrin, Sodium Alginate,

Rubber Cement and Karaya Gum.

• The quantity of oxidizer in the mixture is calculated to supply at least enough oxygen for the complete combustion of the primer, otherwise combustion products that

h f l h fi ld b f d Th F i i ld b d d

Primer Cap CompositionPrimer Cap Composition

Sinoxyd - was first introduced in 1928 as a non-corrosive, non-mercuric primer compound. Today, this serves as the basis for virtually all types of modern primer mixes.

Lead Styphnate 25-55%Barium Nitrate 24-25%Lead Dioxide 5-

10%Antimony Sulfide 0-10%Calcium Sulfide 3-15%Tetracene 0.5-5%Glass Powder 0-

*Note that Lead Styphnate & Barium Nitrate together typically make up 60% to 80% of the total weight.

Reference: Wallace, Jim S. AFTE Journal vol. 22 num. 4, Oct. 1990 pg. 364-389

Completed CasesCompleted Cases

! Total Number of GSR Kits Completed: 1156

! Total Number of GSR Cases Competed: 756

! Total Number of Stubs: 3540

! Total Number of Stubs from:– Clothing: 289– Other: 18

Lab Stats from 1997 to Present

Total Number of Stubs: 5,051

Total Number of Cases: 1164

TriTri--Tech Collection StubsTech Collection Stubs

http://www.tritechusa.com

Primer Gunshot Residue Collection Procedures

! Agencies are now collecting GSR from surfaces other than a suspected shooter's hands. The GSR-SEM/SUR(C) Surface Collection Kit is designed for this purpose and simplifies collection and assures the crime laboratory receives GSR samples that are clearly identifiable, (i.e. collected from table top, dashboard, door frame, clothing, etc.)

Four Stub Surface Collection Kit Four Stub Surface Collection Kit

SEM ChamberSEM Chamber

• Electron Mirror from Charged Nylon Screw

SEM/EDXSEM/EDX--Advanced Advanced Technology Technology

! JEOL 5800! Oxford ISIS

PP--GSR Morphological GSR Morphological CharacteristicsCharacteristics

! Molten Metal Appearance

! Generally Size Ranges Between 10 umto 0.2 um

! Spherical! Amorphous! Pitted or

Dimpled

PP--GSR SEM/EDX SetGSR SEM/EDX Set--UpUp

! 30% Deadtime! >10,000 Counts! Acquisition Rate

Process Time of 2

! 129 eVResolution

PP--GSR SEM/EDX SetGSR SEM/EDX Set--UpUpOperator: Michael V. MartinezClient: 549/03 ROYAL CAYMAN ISLAND POLICEJob: 03-03076Res: Fine Label: (untitled) (9 Oct 03 10:10:42)Microscope conditions

Stage Position:X = 20.85 mmY = -2.481 mmZ = 9.985 mm

Magnification: 350 XAccelerating voltage: 20 kVWorking distance: 11 mmBeam current: 1E-09 A

Backscatter SetBackscatter Set--UpUp

! Manganese and

Rhodium! Alternative:

Iron Sulfide and

Palladium

periodic table

Backscatter ValidationBackscatter Validation

! Gold Standard

! Synthetic PbSbBaStandard

PP--GSR Automated RunGSR Automated Run

Manual Confirmation RequiredManual Confirmation Required

The auto-identification software frequently incorrectly identifies Antimony in place of Tin

PP--GSR ConfirmationGSR Confirmation

Occupation StudyOccupation Study

Objectives

•Prevalence of P-GSR in Environment

• Presence of P-GSR in General Population

Occupation StudyOccupation Study

! 102 People Sampled– Random Population taken from Jury Pool

! Gender– Male: 69– Female: 29– Unknown: 2

! Fired a Weapon in 24 hours– No: 96– Yes: 2– Unknown: 2

PROFESSIONAL GOVERNMENT LABOR INDUSTRY BUSINESS INDUSTRYEngineer 2 Baliff 2 Construction Manager 1 Business Manager 1Accountant 1 Peace Officer 1 Carpenter 1 Management 2Attorney 2 Federal Prosecuter 1 Sheet Metal 1 Technichian 1Scientist 1 City Employee 1 Mechanic 1 Appointment Setter 1Counselor 1 Military 1 Building Demolition 1 Instruction Assistant 1Civil Engineer 1 Election Forman 1 Fiber Glass 1Accounting Executive 1 Civil Service 1 Heat/ Air Conditioning 1Teacher 1 Mail Carrier 1 Construction Electrician 1Contractor 1 Carpenter/ Farmer 1

RESTAURAUNT INDUSTRY MEDICAL INDUSTRY MOTOR INDUSTRYSeafood Manager 1 Nurse's Aid 1 Truck Driver 1Restaurant Manager 1 Nurse 2 Forklift Driver 1Bartender 1 Dark Room X-Ray 1 Car Audio Installer 1Food Service 1 Stenagrapher 1 Airbag Technician 1Butcher 1 Dentist 1 Bus Driver 1Food Wholesaler 1 Pharmacy 1 Jet Engineer Technician 1

Home Health 1 Bus Assistant 1Claims Adjuster 1

DOMESTIC INDUSTRY RETAIL INDUSTRY COMPUTER INDUSTRYNanny 1 Sales Manager 1 Computer Analysis 1Housewife 8 Sales 2 System Analysis 1Student 4 Customer Service 1 Software Engineer 1Hair Dresser 1 Retail Sales 1 Graphic Artist 1Childcare 1 Clerk 1 Computer operator 1Plant Care 1 Shipping 1 Computer 1Retired 12 Cashier 2Unemployed 2

Occupation StudyOccupation Study-- ResultsResults

! Two (2) Subjects Admitted Firing a Weapon or Handling a Previously Fired Weapon within a 24 Hour Period.

! Gender– Both Male

! Occupation– Contactor/Farmer– Carpenter

! Results– Contactor/Farmer: One (1) PbSb Particle Identified– Carpenter: None

Occupational StudyOccupational Study--ResultsResults

! Contactor/Farmer: One (1) PbSb Particle Identified– Sighting in Rifle for Hunting Season >12 Hours

Prior! Validation that P-GSR is not Ubiquitous in

Environment or General Population! Lead was Present on all Individuals

– Tin was also present on over 50% of Individuals

Magistrate StudyMagistrate Study

• Prevalence of P-GSR on an Isolated Sub-Population

Magistrate StudyMagistrate Study

! 100 Subjects Sampled on Dominate Hand! Subjects were in Custody by Local Law

Enforcement, Handcuffed, and Transported to Magistrate Court/Jail Awaiting Arraignment.

! Gender– Male: 78– Female: 22

Magistrate StudyMagistrate Study-- ResultsResults

! Dominate Hand– Right Hand: 91

• 7 PbBa• 6 PbSb

– Left Hand: 9• 2 PbBa

! Gender– Male: 78

• 9 PbBa• 6 Pbsb

– Female: 22• 0

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Subjects(+) PbBa(+) PbSb

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17-25 26-35 36-45 46-70 Unknown

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Magistrate StudyMagistrate Study-- ResultsResults

Washed Hands Subjects (+) PbBa (+) PbSbYes 14No 82 8 6Unknown 4 1

! 16% had PbBa and/or PbSb on Dominate, Unwashed Hand

Magistrate StudyMagistrate Study-- ResultsResults

! Copper (Cu) was Present on 100% of Subjects

! Iron (Fe) was Present on 78% of Subjects! Titanium (Ti) was Present on 59% of

Subjects! Strontium was Present on 34% of Subjects! Tin (Sn) was Present on 16% of Subjects;

(Sb5)- None! Lead (Pb5) was Present on 54% of

Subjects

Magistrate StudyMagistrate Study-- ConclusionsConclusions

! Limitations:– Unable to ask about Specific details of Arrest– Unable to Ask if Subjects Discharged a

Firearm due to Legal Constraints! Identification of Elemental Cu and Fe is

Ubiquitous for this sub-population in South Texas

! ~50% Decrease in Elemental Lead (Pb) when Threshold Limitation was set at 5% (Pb5) as Compared to Occupational Study

Magistrate StudyMagistrate Study-- ConclusionsConclusions

! Secondary or Tertiary Transfer of P-GSR– Contact with Shooter

• From Officer• From Inanimate Objects• From Back of Police Car Seat

Law Enforcement StudyLaw Enforcement Study--(Revisited)(Revisited)

Officers, Their Weapons and Their Hands: An Empirical Study of GSR on the Hands of Non-Shooting Police Officers. Gialamas DM, Rhodes EF, Sugarman LA . 1995;40(6): 1086-1089.

Law Enforcement StudyLaw Enforcement Study--(Revisited)(Revisited)

! 43 Police Officers and Sheriff Deputies were Sampled

! 7% had PbSbBa on Hands (3 Total)! 30% had PbSb and/or PbSbBa (13 Total)! 3 out of 13 did not Wash Hands After Firing a

Weapon (23%) ! Firearm

– 2- used 38 Spl. – 11- used 9 mm

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1 2 3 4 5 6 7 8 9 10 11 12 13

Number with P-GSR on Hands

Ho

urs Hours Since Handled

Hours Since Hand Wash

Suicide StudySuicide Study

Suicide StudySuicide Study

! 126 People Studied! Of those with P-GSR Detected:

– Right Back: 48– Right Palm: 45– Left Back: 33– Left Palm: 40

Suicide Study

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Number StudiedNo P-GSR Detected

Particle Distribution

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PbSbBa SbBa PbSb PbBa

Right BackRight PalmLeft BackLeft Palm

Suicide Study ConclusionSuicide Study Conclusion

! 38% had No P-GSR Detected! Possible Reasons:

– Copious Amounts of Blood on Hands Masking Particles

– New or Clean Weapon, One (1) round Discharged

– Wrong Interpretation by Medical Examiners

– Improper Collection

Report ConclusionsReport Conclusions! No Threshold Limitation on Number of

Particles Identified, i.e. PbBaSb, SbBa, PbBaor PbSb.

! Based on Morphology and Chemical Composition, John D. Smith May Have Discharged a Firearm, Handled a Discharged Firearm or was in Close Proximity to a Discharged Firearm.

! Disclaimer:– It is recommended that the firearm and

ammunition be submitted if further testing is desired.

Contamination StudyContamination Study

Contamination StudyContamination Study

! On Going Tests to Determine “Hot Zones” in Laboratory– Random Samplings of Various Regions

in the Crime Laboratory– Targeting Frequently Entered Work

Areas ! P-GSR Sample Stubs were Placed in

Rooms and Collected from Various Surfaces

Contamination StudyContamination Study-- ResultsResults

! Many P-GSR Particles Containing PbSbBa, SbBa, PbSb and PbBa were Identified from the Following Regions:– Firearm Section

• Indoor Shooting Range and Tank• Work Area• Administration Area• Dust Collected from Air Vents

Contamination StudyContamination Study--ConclusionConclusion! Obtained Building Blueprints to Follow Air

Handlers Intake Flow! SOP: Prohibited from SEM/EDX Room if

Forensic Scientist has Previously Been in Contact with Firearm Section

! No P-GSR Identified in SEM/EDX Room or Trace Area– Sample Areas

• Vents• Table Tops• Door Handles• SEM Chamber• Lab Coats

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