gbi-dofs trace evidence section

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GBI‐DOFS Trace Evidence Section

Michael McCarriagher Manager

404‐270‐[email protected]

• Hair

• Physical (Fracture)

Match (FM)

• Fibers/Textiles

• Paints/Coatings

• Plastics/Polymers

• Glass

• General Materials (GM)

• Gunshot Primer Residue (GSR)

• Processing (collection)

Trace Evidence Services

• Edmond Locard

• Objects or surfaces which come into contact may exchange matter (trace evidence)

• The silent witness

Locard Exchange Principle

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“Gunshot Residue”

• Gunshot Residue –anything emitted from a firearm upon discharge

• Partially burnt gunpowder (organic)• Firearms section‐ “distance determinations” “muzzle to target”

• “How close were the shooter and victim?”

• Particles from primer (inorganic)• Trace Evidence section‐ GSR hand kits• “Was this person present when a gun was discharged?”

• Better name “Gunshot Primer Residue”• Detonation of the primer metals creates these particles

Gunshot Primer Residue

What do we look for?• Particles characteristics of gunshot primer residue

• Particles composed of lead, barium, and antimony

• Particles have molten shape and are about 1 micron in size

• No additional elements that are foreign to ammunition

What does it mean when we find it?

The subject discharged a gun OR

The subject was near a gun when someone else discharged it OR

The subject handled an item that had primer residue on it

What does it mean when we don’t?

The subject was not involved in a shooting incident OR

Primer residue was not longer present at time of collection


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Bang! Now where does the primer residue settle on the ground?


Victim’s of gunshot wounds?

• The GBI does not routinely examine GSR kits from victims of gunshot wounds (Since 2009)

• GBI‐ GSR is found on the hands of 75% of individuals shot by someone else• Colorado‐ GSR is found on the hands of 80% of individuals shot by someone

else

• The GSR kit of the victim cannot distinguish between a homicide and a suicide

• GBI‐ GSR is found on the hands of 88% of suicide victims• Virginia‐ GSR is found on the hands of 87% of suicide victims• Cincinnati‐ GSR is found on the hands of 79% of suicide victims• Bexar Co (TX)‐ GSR is found on the hands of 38% of suicide victims


• “I know this guy is the shooter, why didn’t you find anything?”

• GSR does not last forever 8‐10 hour maximum

• Police officers don’t always take kits immediately

• On occasion subjects are allowed to wash their hands


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• GSR on clothing is not a routine analysis. Please call ahead. Any exams are a sampling of the garment. Can’t associate with a certain incident.

• GSR on vehicles is not a routine analysis. Please call ahead.• When collecting GSR from vehicles (drive‐bys) use stubs (not swabs) in GSR kits to

sample from the headliner area above each window. Treat the control the same way you would for hands.

• Do not collect GSR from seats, door handles, steering wheels, or shifters.

Gunshot Primer Residue Case

• Seven suspects involved• Back door/basement of a residence kicked in• Teenager Nick Jackson was in basement playing video games

• Suspects shoot teenager• Van pulled over a short distance from the scene occupied by the suspects

• What were the involvement of each suspect?• And why was this house the target of a home invasion?

• Six GSR Kits were submitted to the laboratory from…• Anthony Lumpkin

• Jason Dozier

• Reco West

• Michael Davis

• Eddie Green

• Timothy Johnson


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Davis was accused of being the fourth individual that entered the basement



• So why was this home selected for a large home invasion…..

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Class Evidence vs. Identification/Individualization

• Class Evidence• QUESTIONED material is like the KNOWNmaterial and therefore came from the same source as the known material or another source just like it

• Glass, Fiber, Hair, Paint, Plastic

• Identification/Individualization• Nuclear DNA

• Fingerprints

• Firearms

• Fracture Match

Physical (Fracture) Match• Anything Broken, Torn, Cut, or Separated

• Automotive pieces, duct tape, trash bags, etc

“The broken pieces of plastic recovered from the scene of the accident originated from and were one time a part of the submitted head light assembly from the Dodge Charger Vin #1234567890”

Physical (Fracture) Match

• A woman is reported missing by her husband, at the behest of her family members

• About 10 days later she is found under a pile of tires behind an auto shop, concealed in orange trash bags.

• She works for a trash bag manufacturer. One roll from their home submitted to the lab.

• The husband is the suspect.

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Conclusion written on report:

Examination and comparison of the inner most bag from the body (1D) and one orange trash bag from the master bedroom (9B) revealed corresponding fracture contours and surface detail. It is therefore concluded that item 1D originated from and was at one time a part of item 9B.


• Other cool examples

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Paints and Coatings

How can this exam help?

• Automotive‐ vehicular homicides/hit and runs

• Architectural‐ breaking and entering or vandalism

• Investigative leads and Comparisons

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Hit and Run –No suspect• To provide investigative lead information

• Examine clothing from victim

• Smears of paint are indicative of forceful contact

• Paint chips in debris can possibly provide vehicle information

• Search PDQ (paint data query) database using questioned paint chip

• Can narrow down to manufacturer, plant, color, vehicle model and year

PDQ database –Investigative lead search• User populated database run by the RCMP

• Collect 60 samples per year from damaged vehicles to submit

• Representative of vehicles on the road/ paint systems being used by manufacturers

• Search based on chemistry of paint layers from an unknown source

• Narrow down hit list to possible vehicle make, model and year information

“Your search for a suspect vehicle should be concentrated on, but not limited to the following vehicles…”

• Automotive: • Collect within 1 inch of damaged area• Collect standard from every damaged panel of vehicle• Use scalpel or sharp blade to scrape paint from metal substrate making sure to remove all layers of paint down to the metal

• Cut piece of plastic area (ie bumper) or scrape down to and including the plastic substrate

• Architectural:• Collect within 1 inch of damaged area• Scrape paint down to the substrate to remove all layers of paint

• Miscellaneous:• Submit paint can• Submit painted tool

Paint comparisons –Collection of known samples

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Case example –Hit and Run with Suspect

• Bicyclist struck by vehicle and vehicle left scene

• Items submitted:

‐victim’s clothing

‐victim’s bike

‐front fender from suspect’s vehicle

‐hood from suspect’s vehicle

• Stereomicroscopic examination


Rear tire of bike Questioned paint recovered from bike

Smear on pants

• Other fragments of paint found in debris from clothing• Full layer structure fragment adhered to bike tire indicative of

forceful contact therefore chosen for detailed comparison

• Determine layer structure

• Cross section of paints

• Comparison microscope

• Compare layer structure

• Examine colors and other features such as pigments in each layer


Front fender Q from bike

Hood

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• Analysis to compare the binder portion of the paint using FTIR and PGC

• Determining at each step if we can distinguish between the questioned and the known paint

• Some variation expected within paint

• IR spectra is also used to classify type of paint (ie acrylic, alkyd, urethane)


Known

Questioned


PGC/MS comparison

Known Questioned

• SEM/EDS to analyze the elements that are present in each layer of the paint

• Based on the pigments and extenders used (ie TiO2, clay)

• Compare overlay of known and questioned


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Paint

• Conclusion written on report:• The questioned paint recovered from the bicycle’s rear tire is the same distinct type of paint as layers 1‐5 of the known paint on the suspect vehicle’s fender and originated either from that source or another source of automotive paint having the same distinct characteristics.

• The suspect vehicle hood cannot be eliminated as a possible source of the questioned paint recovered from the khaki pants.

• What does this mean to you as a prosecutor…..• Published study. Estimated discrimination level of a paint exam exceeds 99.999%. 200 vehicles sampled. 19,900 pairwise comparisons. 1 undifferentiated pair.

Plastics/Polymers

• Tapes• Duct tapes

• Electrical tapes

• Packaging Tapes

• Vehicle Parts, often painted• Bumpers

• Fenders

• Adhesives

• Rubber

• Plastic bags

• Zip ties

Plastics and Polymer (Tape Example)

• A home invasion/murder was perpetrated by two subjects.

• 82 year old victim was bound with tape and killed via blunt force trauma

• Subjects were identified and seen on video at a store buying tape.

• The suspected roll of tape used was not recovered. But investigators did purchase four rolls of the same tape from the same store to be used as a known.

• Fracture match is not an option. But a compositional comparison of the tape is….

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Chemical/Elemental analysis was performed on each of these components and comparisons were done.


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Glass

Real Case Scenario

Drive by shooting kills a 19 year old female. Shattered glass found in roadway where shooting took place (questioned sample).

Two days later a stolen Kia was found abandoned. Vehicle had casings inside and a broken out rear window. Some of this glass was recovered (known sample).

Glass

10‐ known glass from vehicle11‐ questioned glass from roadway

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Glass

Glass

Glass

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Glass

• Conclusion written on report:

• Three glass fragments identified as recovered from XXX Avenue (item 11) either originated from the Kia (item 10) or another source of broken glass possessing the same distinct physical, optical, and chemical characteristics.

• What does this mean to you as a prosecutor…..

Glass Significance

• Published round robin study‐ Can differentiate approx. 97% of glasses from each other

• GBI Reference Collection of 250 samples

Trace Evidence “Processing”

• The recovery and preservation of questioned hairs/fibers

• Tape lifting

• Scraping

• Stereomicroscope/forceps

• Performed prior to serology/DNA examinations

• Dedicated exam rooms• Keep subject(s)/victim(s) separate

• Keep scenes separate

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o Animal or Human

o Race ‐ Negroid, Caucasian, Mongoloid

o Body Area ‐ Head, Pubic, Body

o Microscopical Comparisons (head and pubic)

o Follicular Material/nuclear DNA

o No Follicular Material/mitochondrial DNA

• Hair exams are only performed on violent offense cases.

Known Hair

Questioned Hair

Hair Examinations

Standards for Hair Comparisons(Known Hair)

• Adequate hair standard represents the variation of characteristics within a single person’s hair

• Minimum of 25 randomly sampled hairs (include root)

• Use a fine toothed comb to repeatedly comb the area of interest (head or pubic)

• Obtain additional hairs by randomly pulling with fingers

• Do not use forceps to pull hair as this may damage the hair

• Collect as close to the incident as possible

Hair Examinations

“Two pubic hairs from the underwear originated from Joe Smith or

someone with hair possessing the same distinct microscopic characteristics.

It should be noted that microscopical hair comparisons do not constitute a

basis for absolute personal identification. Additional testing of nuclear or

mitochondrial DNA from the hair has the potential to eliminate Joe Smith

as a potential donor or increase the significance of the hair association

based on microscopy alone.”

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How can this exam help you?

• Who was wearing a garment? • Example‐armed robbery with a ski mask left behind

• Who was sitting in a car?• Example‐ Drive by shooting. Tape lift seats/head rests

• Violent crimes with contact between individuals• Example‐ Sexual assaults‐transfer of head or pubic hair

Hair Examinations

Nuclear DNA from a Hair

• Traditionally requires an actively growing root (antigen) or an inactive root (catagen/telogen) that has follicular material attached.

Antigen Cat/Tel Cat/Tel w/ follicular

Nuclear DNA from a Hair

• Majority of hairs encountered in Trace Evidence section are CT hairs without the follicle making them not suitable to even attempt nDNAtesting.

• Success rate for obtaining a nDNA profile when a hair root is clipped is approximately 15‐20%

15‐20%

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Mitochondrial DNA from Hair

• Can be obtained from the shaft making it more robust

• Maternally inherited

• Statistics not nearly as impressive as nuclear DNA (an example will be shown later)

• Not performed at the GBI. Request can be made to the FBI.

Mitochondrial DNA from Hair

• Can be obtained from the shaft making it more robust

• Maternally inherited

• Statistics not nearly as impressive as nuclear DNA (an example will be shown later)

• Not performed at the GBI. Request can be made to the FBI.

Fibers/Textiles

• Fabric Comparisons

• Ropes and Cordage

• Single Fiber Comparisons

• Fabric Impressions

• Indication of Force (Cut vs Torn)

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Fibers/Textiles

Known fiber standards should be submitted. Fiber standards can be garments, sections of carpet/upholstery, or ropes and cordage

“Purple polyester questioned fibers from the windshield originated from the jacket or another source of textile material possessing fibers with the same distinct microscopic, optical, and chemical characteristics.”

Case #1‐Skylar Dials Case

Hair/Fiber Skylar Dials

Victim

Carpet

Blanket

Tape lifts of bedroom

Collett’s Clothes

Collett’s bedroom

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Hair‐Skylar Dials


Victim

Carpet

Blanket


Collett’s Bedroom

Collett’s Clothes

Fiber‐Skylar Dials• 58 fibers recovered from Collett’s clothes or bedroom consistent with

Dials’ sweater (a blend of several fiber types)

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Fiber‐Skylar Dials• 58 fibers recovered from Collett’s clothes or bedroom consistent with

Dials’ sweater (a blend of several fiber types)


Victim

Carpet

Blanket


Collett’s Bedroom

Collett’s Clothes

Fiber‐Skylar Dials• 5 fibers recovered from Collett’s clothes or bedroom consistent with Dials’ pants

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Victim

Carpet

Blanket


Collett’s Bedroom

Collett’s Clothes

Fiber‐Skylar Dials• 1 fiber recovered from Collett’s bedroom consistent with Dials’ shirt


Victim

Carpet

Blanket


Collett’s Bedroom

Collett’s Clothes

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Fiber‐Skylar Dials• 1 fiber recovered from Dials’ body consistent with Collett’s bedroom carpet


Victim

Carpet

Blanket


Collett’s Bedroom

Collett’s Clothes

Fiber‐Skylar Dials• 7 fibers recovered from Dials’ clothing is consistent with Collett’s blanket

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Victim

Carpet

Blanket


Collett’s Bedroom

Collett’s Clothes

Fiber‐Skylar Dials• 8 fibers recovered from Dials’ clothing is consistent with Collett’s jacket


Victim

Carpet

Blanket


Collett’s Bedroom

Collett’s Clothes

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Skylar Dials Case

Guilty- Sentenced To Life with No Parole

Questions?

Michael McCarriagher Manager

404‐270‐[email protected]

gbi-dofs trace evidence section

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