Topic: Ballistic Fingerprinting discussion

[Scott Doyle]

Ballistic Fingerprinting discussion started by jultemp
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Posted by: jultemp on Oct. 21 2002,10:55

Can an firearms expert please address the current discussion about ballistic fingerprinting?  All I see are politicians debating each other but I'd like to see views from real firearms experts.
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Posted by: Mitchr on Oct. 23 2002,06:36

jultep,  If you would identify a specific aspect of the "current discussion" it might be easier for an examiner to respond.  The discussion regarding the "database" can be quite lengthy.  
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Posted by: ronald on Oct. 23 2002,16:37

I have difficulty accepting anyone's opinion who claims that the process of comparing a bullet to a particular weapon is a "ballistics" examination.  The process has nothing to do with the science of ballistics which is the study of objects in motion not a determination if a bullet came from a weapon. Yet, all of the psuedo experts continue to refer to the process as a ballistic examination, and now we have the "ballistic fingerprint."

No one has bothered to mention that the identification is problematic and is not an exact science but is based upon the skill, training, and experience of the examiner and largely "intuitive" in application.  A nice way of saying its an educated guess.  The notion that modern firearms are made so poorly as to leave an unique mark in each individual barrel is questionable.   In the 35 years I have practiced law as a prosecutor and defense attorney the typical opinion I have encountered by a "expert" is that a bullet may have been fired from a gun, or any other similar model.  I have yet to encounter an expert who said that the recovered bullet came from the subject's gun to the exclusion of every other gun like it.

There is a practical way to put this to a test.  Select 5 rifles of the same model and caliber at random from any manufacturer's production line.  Using the same lot number of ammunition, fire five rounds thru each rifle.  Then allow an examiner to recover his own round from each of the five rifles.
Then have him examine all 25 fired questioned rounds and see how many he can match to each rifle.  I'll bet that the most experienced expert will fail to make a positive match over 50% of the time and probably higher than that.

While the process of doing a firearm forensic examination may be helpful, it is not foolproof.  Just like latent fingerprint exams there are no well-established standards regulating the field.  Where fingerprints are concerned, some agencies require as many as 14 points in order to provide an opinion as to a match.  Some do it with as few as 4 or 5.  Yet, the public does not know that the fewer the points of comparison, the more questionable the opinion becomes.  The same is true with "experts" saying that a bullet may have come from a particular gun just because of the similarity of the class characteristics while omitting to say that any uniqueness present in the gun from the assembly line may be altered over a period of time do to use, misuse, cleaning, etc.

It would be good to hear the experts speak to this issue and if nothing else, tell the uninformed that it is not a ballistics test.
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Posted by: jsdoyle on Oct. 24 2002,06:04

It's not a "ballistics" test.  No where on this site will you see it called that.  We try to make that distinction when ever possible.

The test that you mention has been conducted in a number of studies and contrary to your belief, the "experts" have been able to determine which gun fired the questioned bullets.  

You mention that, "50% would fail to make a positive match".  Well, the failure to make a positive match is not necessarily a wrong answer.  Not all guns leave a unique "fingerprint" on the bullets that pass down thier barrels.  The media would lead you to believe differently.

Firearm Examiners have one of, if not the, longest training period of all of the disciplines of Forensic Science.  This is not by accident.  Those trained in this profession realize that it takes an enormous amount of training in microscopic comparative analysis before one can be considered capable of rendering an opinion in a case.

Virtually all laboratories now have review processes in place that evaluate the work of Firearm Examiners.  We work proficiency tests annually and case work is peer reviewed for accuracy.

(I have to go to work, more to follow, someone else may want to jump in here)
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Posted by: dbonar on May 05 2003,12:39

ronald,

 The community of firearm and toolmark EXPERTS not only has conducted numerous experiments identifying individual firearms from one production run, but we have also published a number of articles that detail the identifiation of bullets to CONSECUTIVELY made barrels.  In other words, we can differentiate between individual firearms that are made one after the other using the same tools!  

 Your inference that firearms must be poorly made to be identifiable is frankly incorrect.  The fact is that even the most well made firearm can leave microscopic marks on a bullet or cartridge case that are suitable to identify that gun to the exclusion of all others.  

 And yes, it is up the the experience and training of the firearm examiner to determine if those marks are present in sufficient quantity and quality to make an identification.  However, is it not the case with every science that one must be trained in the ability to perform the necessary experiments and to interpret the results of those experiments?  I submit that this is the exact procedure used in firearm examination. And if a firearm examiner, with his training and experience, decides that these marks are not present in sufficient quanitity and quality, then his scientific answer must be "inconclusive".  In this case, he will give as much investigative aid, a list of "possible" firearms for instance, as possible based on his scientific observations of the evidence that is presented.   So tell me again how this field is different from a science?

I suggest that maybe before stepping into a scientific arena in which you obviously have very little experience and questioning that field as a science, that you do a bit more research of your own.