9: GSR Flashcards
what are the universal and expanded collection methods of GSR
- hands
- hair
- face
- clothing
- large objects
what is found in the Latent Forensic assembled kit
- canadian forms (instructions for collection and lab submission forms in both english and french)
- this is unlike all the other american made commercial kids
true/false Latent Forensic assembled kit is authorized by the RCMP
true
what 3 particles are found in GSR
- lead
- barium
- antimony
what can we say if we find lead, barium, and antimony
“characteristic of GSR”
what can we say if we find 2/3 of the GSR elements
“consistent with GSR”
current GSR analysis methods use what
scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS)
what does SEM-EDS analyze
only the inorganic components
what are the different levels of hierarchy of proposition for GSR evidence
- offence level (III)
- activity level (II)
- source level (I)
what question is asked at the offence level (III)
did the POI shoot the victim
what are hypothesis of the prosecution and defence at the offence level (III)
- Hp: the POI murdered the victim
- Hd: an unknown person murdered the victim
what question is asked at the activity level (II)
did the POI discharge a firearm
what are hypothesis of the prosecution and defence at the activity level (II)
- Hp: the POI discharged a firearm or the reference combo of firearm ammo
- Hd: an unknown person discharged a firearm or the reference combo of firearm ammo
what question is asked at the source level (I)
is the trace arising from the POI hands GSR
what are hypothesis of the prosecution and defence at the source level (I)
- Hp: the specific trace came from a discharged firearm (is GSR)
- Hd: the specific trace came from a non-related environmental source (is not GSR)
what are the challenged of interpreting GSr
- what is the source of GSR (environmental or not)
- how did it get there (did they shoot, or someone else)
- transfer/ persistence (did it get on your hands cause you shot a gun or cause you shook hands w someone who did)
- activity level info
what are some non-GSR sources of GSR-like particles (environmental sources)
- brake pads
- fireworks
- nail guns
- matches
- exploded airbags
describe the study where they determined the prevalence of GSR on clothing
- looked at the cuffs of 100 garments
- all related to non-firearms offences
____% of garments had Pb/Sb/Ba particles in the study where they determined the prevalence of GSR on clothing
2%
____% of garments did not have any Pb/Sb/Ba particles in the study where they determined the prevalence of GSR on clothing
50%
the probability of finding one of the Pb/Sb/Ba particle on clothing by chance is on the order of _____-
0.01
when does primary transfer occur
during or immediately after a firearm discharges
the initial discharge of a firearm results in the ______ of GSR particles onto surfaces in near proximity
direct deposition
the initial discharge of a firearm results in the direct deposition of GSR particles onto _______
surfaces in near proximity
the shooters hands covered in GSR is a _____ (primary/secondary) source
primary
what may result in GSR being found on a surface that was not present during the initial discharge
contact w surfaces/individuals contaminated w GSR during the primary transfer
what are examples of secondary GSR transfer
- handshake
- touching a surface (recently fired gun- handling the gun)
- clothing clean-to-contaminated (material-to-material)
describe the study where they found the background levels of GSR on police officers
- firearms-carrying PO were randomly sampled for GSR
- then they simulated arrest situations to investigate GSR transfer
in the study where they found the background levels of GSR on police officers, how many of the officers had at least one characteristic particle
~5%
in the study where they found the background levels of GSR on police officers, what was the probability of transfer of a particle
less than 25%
how many GSR particles are typically found
- 0 to 3000
- more likely to be on the low end
with shotguns, are we likely to find GSR near the shooter or on their hand
no
with automatic rifles, are we likely to find GSR near the shooter or on their hand
yes (due to proximity to ejection port and muzzle)
where will be see GSR with shot guns
- not in vicinity of shooter
- not on shooting hand
- lots on supporting hand close to the barrel and in crook of the supporting arm)
where will be see GSR with automatic rifles
both hands
true/false more particle numbers are expected w automatic rifles than with revolvers and pistols
- FALSE
- other way around
true/false there is a rapid loss of GSR in the first few hours after the transfer
true
at what point after GSR transfer will there be basically none left
6-8 hours
the GSR persistence study looked at what ammo and firearm
- high-caliber ammo
- various firearms
what four fabrics were viewed in the study looking at the type of fabric on the collection efficiency of gunshot residues
- cotton
- worn cotton
- leather
- wool/ viscose/ acrylic
why were those fabrics selected in that one study
because of their varying sheddability
what is sheddability
capability of textile to lose fibres
sheddibility of 0 is ____ (low/high) sheddability and ____ (low/high) GSR yield
- low
- high
sheddibility of 5 is ____ (low/high) sheddability and ____ (low/high) GSR yield
- high
- low
rank the following from low to high shed :cotton, worn cotton, leather, wool/ viscose/ acrylic
- leather (1)
- cotton and worn cotton (3)
- wool/ viscose/ acrylic (4-5)
describe that one fabric study
- fabric was placed in the shooting range
- no air circulation
- 2m from the firearm
- each round was done independently
- high variability was seen between diff rounds performed w the same weapon
leather had _____ times ___ (higher/lower) GSR than cotton
~3.5x higher
wool/ viscose/ acrylic had _____ times ___ (higher/lower) GSR than cotton
0.6x lower
true/false cotton reference and worn cotton had similar GSR levels
true
GSR deposition is _______ (heterogenous/ homogenous)
heterogenous
the longer the distance, the _____ (more/less) GSR present
less
in the shooting distance study, at what distance are there only 400 GSR particles
50cm
in the fabric study, how many particles were detected on cotton
- 0.9 characteristic
- 1 characteristic and consistent
in the fabric study, how many particles were detected on leather
- 3.3 characteristic
- 3.7 characteristic and consistent
in the fabric study, how many particles were detected on wool
- 0.6 characteristic
- 0.7 characteristic and consistent
in the GSR location study, what trend was seen for the front upper parts of upper clothing
- low of all characteristic chemicals (all less than 1)
- more of the individual chemicals, and less of the dual, and less of trio
- very little Ba
in the GSR location study, what trend was seen for the sleeves
- low of all characteristic chemicals (all less than 1)
- more of the individual chemicals, and less of the dual, and less of trio
- basically no Ba, and no duals with Ba
in the GSR location study, what trend was seen for the hands
- low of all characteristic chemicals (all less than 1)
- lots more Sb than anything else (its about 0.9, everything else is 0.1)
In R v Glasgow 2022, what did Dr. Hearn confirm
- in his opinion
- the particles identified as GSR originated from a firearm
In R v Glasgow 2022, was there a significant amount of GSR
- the expert says its hard build a conclusion
- but it was either exposed to discharge
- or recently exposed to another source of GSR
In R v Glasgow 2022, how many particles characteristic of GSR were found
9
In R v Glasgow 2022, where was the GSR sampled from
the interior of a vehicle
In R v Woodcock et al. 2008, what was said about the presence of GSR
- indicated the person either discharged a firearm
- was in close proximity ro a firearm when it was discharged
- or came into contact w a surface that had GSR on it
In R v Woodcock et al. 2008, did they say if the number of particles showed the person was nearby a gun
the number of particles found on a person was not determinative about whether or not they fired a gun or were nearby
In R v Woodcock et al. 2008, how long does it take for 1/2 of GSR on someone to be lost
every 30-60 mins
In R v Woodcock et al. 2008, what directions did they say GSR can go
- forward
- sidewards
- backwards
In R v Woodcock et al. 2008, how far can GSR travel
upwards of 60ft
In R v Woodcock et al. 2008, how far can GSR travel behind the discharged firearm if there was wind
30ft behind
In R v Woodcock et al. 2008, did they say GSR can be readily transferred between 2 objects
yes
In R v Admasu 2021, what did police sample
the hands of Mr. Admasu and Mr Wawryk
In R v Woodcock et al. 2008, where were the samples submitted to
RCMP forensic science and identification lab in Ottawa
In R v Woodcock et al. 2008, how many sampling stubs were taken
8 total
In R v Woodcock et al. 2008, what was used to test
scanning electron microscope coupled with an energy dispersive x-ray spectrometer
In R v Woodcock et al. 2008, how much GSR was found on Mr. Admasu’s hands
- 1 particle characteristic of GSR on right hand
- 2 particles on left hand
In R v Woodcock et al. 2008, how much GSR was found on Mr Wawryk’s hands
no GSR on either of the hands
In R v Amankwa and Nyadu 2017, where were the samples taken from
- web of the hand along the index finger and thumb
- second sample from the back of the hand
- for both left and right ahnds
In R v Amankwa and Nyadu 2017, where were the samples submitted to
centre of forensic science
true/false standard practice involves sampling the palms of the hands
false
In R v Amankwa and Nyadu 2017, how much GSR was found on Mr. Nyadu
3 GSR were identified
In R v Amankwa and Nyadu 2017, how much GSR was found on Mr. Amankwa
no GSR found
In R v Amankwa and Nyadu 2017, what was the timeline
- Mr Nyadu arrested at 2:41am
- officer performed GSR test at 5:59am
- time window of under 3h
In R v Amankwa and Nyadu 2017, what were the possible explanations of GSR found on someone’s hands
- the person recently discharged a firearm
- the person was in close proximity when a firearm was discharged
- the person had the particles transferred tot heir hands from contect with another contaminated surface
In R v Amankwa and Nyadu 2017, what did the expert indicate was the most likely explanation for the GSR being present
he cold not indicate if one was more likely than the other
when was OGSR made
1982
what is OGSR
- new primer mixture for the manufacture of ammunitions called Sintox
- produced by Dynamit Nobel AG
- was known as lead-free or heavy-metal free primer
- was designed to minimize airborne heavy metal, like Pb, Ba and Sb, to avoid health and environmental issues, especially in firing ranged and during hunting seasons
true/false the composition of diff ammo varies
true
true/false the 4-NDPA conc varies between ammo
true
what does OGSR stand for
organic GSR
why were there such large error bars on the GSR graphs
cause the heterogenous nature just introduces big variability
in OGSR, there is ____ (less/more) DPA than 4-NDPA
more
what is inside 4-NDPA
- nitro group
- 2 phenyl
- and amine
- nitrodiphenylamine
what is inside DPA
- 2 phenyl
- and amine
- diphenylamine
- same thing at 4-NDPA but without the nitro
what is the difference between OGSR and IGSR
- OGSR has a single discharge
- had DPA and 4-NDPA
- more than 100 particles of PbSbBa
true/false conc of OGSR decreases over time
true
how much OGSR is lost after 2 hours
80%
how long does it take to lose 80% of OGSR
2 hours
