Forensic Science AMAScience AMA Series: Hi, Im Dr. Suzanne Bell, Associate Professor of Chemistry and Forensic Science at WVU. Lets talk about the chemistry of firearms. (self.science)
submitted 10 hours ago * by SuzanneBell_ACSProfessor of Chemistry and Forensic Science|WVU
Hi, Im Dr. Suzanne Bell, Associate Professor of Chemistry and Forensic Science at WVU. Lets talk about the chemistry of firearms.
Introduction
Im Suzanne Bell, Associate Professor of Chemistry and Forensic Science at West Virginia University. I teach and conduct research in analytical and forensic chemistry and work with students from undergraduate through PhD. I joined the faculty here in 2003. Prior to then, I worked for the New Mexico State Police Crime Laboratory, Los Alamos National Laboratory, and Eastern Washington University. My PhD is from New Mexico State University.
I am a past member of the Scientific Working Group for Seized Drug Analysis (SWGDRUG) and a current member of the Scientific Working Group for Gunshot Residue (SWGGSR) and the gunshot residue subcommittee of NISTs Organization of Scientific Area Committees (OSAC). I am also a commission on the National Commission on Forensic Science (NCFS) and the Forensic Education Programs Accreditation Commission (FEPAC).
When a gun is fired, a wealth of chemical and physical evidence is produced. This residue is deposited on surfaces near the shooter including then hands. The chemical evidence is a complex combination ranging from tiny particulates containing heavy metal oxides and sulfides, particles of burnt and partially burnt propellant, and condensed gases. Each type of evidence can be characterized analytically and used to help answer key forensic questions such as who did (or did not) fire the weapon.
I will be speaking at an upcoming webinar with the American Chemical Society on Thursday, May 14 at 2pm ET. Everyone is welcome to join: http://www.acs.org/content/acs/en/events/upcoming-acs-webinars/gunshot-chemistry.html
I am ready to answer your questions about forensic chemistry and how we apply it in shooting cases.
Resources and weblinks:
NCFS: http://www.justice.gov/ncfs FEPAC: http://fepac-edu.org/ SWGGSR: http://www.swggsr.org/ OSACS: http://www.nist.gov/forensics/osac/ WVU Chemistry: http://chemistry.wvu.edu/ WVU Forensic and Investigative Sciences: http://forensics.wvu.edu/
I'll be back at 12 pm EDT (9 am PDT, 5 pm UTC) to answer your questions, ask me anything!
Glad to see all the questions appearing. I will be on-line at noon EST.
A couple of notes: I work in chemistry and not ballistics or tool marks. I dont work with the markings that are imparted to bullets or cartridges or comparing bullets to weapons. I am familiar with these areas and will offer comments as appropriate but I am not a court qualified expert in these fields.
I will see you all at noon.
Good afternoon (or morning, depending on where you are). I am happy to see all the questions! I will try to get to as many as I can.
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[]Claidheamhmor 105 points 10 hours ago
What sort of misconceptions do you see in movies and TV?
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[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science| WVU 151 points 8 hours ago
Typically it would be how fast analyses get done. Casework takes time and even with instruments that work rapidly, there is much more that goes into casework that is not shown. However, I don't knock the shows or movies - they are meant as entertainment and they help to get folks interested in science, that's great.
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[]_swordBA|Physics and Mathematics 21 points 10 hours ago
Perhaps too specific or otherwise already answered, but is it realistically possible to correlate the residue found on a shooter and / or firearm with the residue found within / surrounding the wound of a victim? I imagine doing so would be quite difficult, but I'm curious if enough information could be teased out of a wound to identify the exact ammunition used (i.e. powder and projectile composition, not just caliber).
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[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science| WVU 24 points 8 hours ago
It is possible to identify residues around wounds but I don't know of anyone who has tried to correlate this material to that recovered from another person. The residues won't tell you about caliber or projectile composition.
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[]brocktice 33 points 10 hours ago
Given the barrel of a recently-fired gun, how accurately can you determine which brands/mixes of powder were used in those recently-fired shots? What about a barrel that has been swabbed normally to a mirror finish? Do polygonal barrels affect this information recovery as compared with normal land and groove rifling?
Thanks!
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[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science| WVU 30 points 8 hours ago
In general, determining the exact brand of a propellant would be challenging. We focus on compounds that we expect to see across brands. I am not familiar with any published studies that have attempted to identify the brands from residue.
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[]GeorgedaflashGlass 93 points 10 hours ago
Is it possible for someone who hasn't shot a gun to possess a residue pattern similar to someone who has shot a gun? For instance, you and I are standing in line waiting for someone to finish up at the atm, you walk up next to me, literally shoulder to shoulder and shoot the person at the atm. You leave and I stay, am I losing the trial?
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[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science|WVU 48 points 8 hours ago
When a firearm is discharged, the residues disperse and will be deposited on whatever surfaces are close by. The closer to the discharge point (in general), the more the initial deposit would be expected.
http://www.reddit.com/r/science/comments/35pi9d/science_ama_series_hi_im_dr_suzanne_bell/
submitted 10 hours ago * by SuzanneBell_ACSProfessor of Chemistry and Forensic Science|WVU
Hi, Im Dr. Suzanne Bell, Associate Professor of Chemistry and Forensic Science at WVU. Lets talk about the chemistry of firearms.
Introduction
Im Suzanne Bell, Associate Professor of Chemistry and Forensic Science at West Virginia University. I teach and conduct research in analytical and forensic chemistry and work with students from undergraduate through PhD. I joined the faculty here in 2003. Prior to then, I worked for the New Mexico State Police Crime Laboratory, Los Alamos National Laboratory, and Eastern Washington University. My PhD is from New Mexico State University.
I am a past member of the Scientific Working Group for Seized Drug Analysis (SWGDRUG) and a current member of the Scientific Working Group for Gunshot Residue (SWGGSR) and the gunshot residue subcommittee of NISTs Organization of Scientific Area Committees (OSAC). I am also a commission on the National Commission on Forensic Science (NCFS) and the Forensic Education Programs Accreditation Commission (FEPAC).
When a gun is fired, a wealth of chemical and physical evidence is produced. This residue is deposited on surfaces near the shooter including then hands. The chemical evidence is a complex combination ranging from tiny particulates containing heavy metal oxides and sulfides, particles of burnt and partially burnt propellant, and condensed gases. Each type of evidence can be characterized analytically and used to help answer key forensic questions such as who did (or did not) fire the weapon.
I will be speaking at an upcoming webinar with the American Chemical Society on Thursday, May 14 at 2pm ET. Everyone is welcome to join: http://www.acs.org/content/acs/en/events/upcoming-acs-webinars/gunshot-chemistry.html
I am ready to answer your questions about forensic chemistry and how we apply it in shooting cases.
Resources and weblinks:
NCFS: http://www.justice.gov/ncfs FEPAC: http://fepac-edu.org/ SWGGSR: http://www.swggsr.org/ OSACS: http://www.nist.gov/forensics/osac/ WVU Chemistry: http://chemistry.wvu.edu/ WVU Forensic and Investigative Sciences: http://forensics.wvu.edu/
I'll be back at 12 pm EDT (9 am PDT, 5 pm UTC) to answer your questions, ask me anything!
Glad to see all the questions appearing. I will be on-line at noon EST.
A couple of notes: I work in chemistry and not ballistics or tool marks. I dont work with the markings that are imparted to bullets or cartridges or comparing bullets to weapons. I am familiar with these areas and will offer comments as appropriate but I am not a court qualified expert in these fields.
I will see you all at noon.
Good afternoon (or morning, depending on where you are). I am happy to see all the questions! I will try to get to as many as I can.
410 comments
share
top 200 commentsshow all 410
sorted by:
q&a (suggested)
[]Claidheamhmor 105 points 10 hours ago
What sort of misconceptions do you see in movies and TV?
permalink
[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science| WVU
Typically it would be how fast analyses get done. Casework takes time and even with instruments that work rapidly, there is much more that goes into casework that is not shown. However, I don't knock the shows or movies - they are meant as entertainment and they help to get folks interested in science, that's great.
permalink
parent
load more comments (9 replies)
load more comments (38 replies)
[]_swordBA|Physics and Mathematics 21 points 10 hours ago
Perhaps too specific or otherwise already answered, but is it realistically possible to correlate the residue found on a shooter and / or firearm with the residue found within / surrounding the wound of a victim? I imagine doing so would be quite difficult, but I'm curious if enough information could be teased out of a wound to identify the exact ammunition used (i.e. powder and projectile composition, not just caliber).
permalink
[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science| WVU
It is possible to identify residues around wounds but I don't know of anyone who has tried to correlate this material to that recovered from another person. The residues won't tell you about caliber or projectile composition.
permalink
parent
load more comments (8 replies)
[]brocktice 33 points 10 hours ago
Given the barrel of a recently-fired gun, how accurately can you determine which brands/mixes of powder were used in those recently-fired shots? What about a barrel that has been swabbed normally to a mirror finish? Do polygonal barrels affect this information recovery as compared with normal land and groove rifling?
Thanks!
permalink
[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science| WVU
In general, determining the exact brand of a propellant would be challenging. We focus on compounds that we expect to see across brands. I am not familiar with any published studies that have attempted to identify the brands from residue.
permalink
parent
load more comments (2 replies)
[]GeorgedaflashGlass 93 points 10 hours ago
Is it possible for someone who hasn't shot a gun to possess a residue pattern similar to someone who has shot a gun? For instance, you and I are standing in line waiting for someone to finish up at the atm, you walk up next to me, literally shoulder to shoulder and shoot the person at the atm. You leave and I stay, am I losing the trial?
permalink
[]SuzanneBell_ACSProfessor of Chemistry and Forensic Science|WVU
When a firearm is discharged, the residues disperse and will be deposited on whatever surfaces are close by. The closer to the discharge point (in general), the more the initial deposit would be expected.
http://www.reddit.com/r/science/comments/35pi9d/science_ama_series_hi_im_dr_suzanne_bell/
