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Old 21st November 2020, 04:19 PM   #541
Chris_Halkides's Avatar
Join Date: Dec 2009
Posts: 9,975
"A Path Forward" on tool mark analysis

Originally Posted by JTF View Post
You certainly have the right to give a hand wave to the talking points in my post, but your mix of pot shots with selective commentary (e.g., Luminol issue only), provides me with ample motivation to put forth the following challenge(s).

1) Please point out why the following statement in my post is "highly misleading."

"Subsequent testing was unable to produce a definitive source for the Luminol reaction, but analysts were able to determine that the concrete floor had been cleaned with bleach and pain thinner."

3) Please point out why the following statement(s) in my post are "highly misleading."

"Dassey constructed a drawing of his uncle's garage depicting Halbach, Avery, and Dassey in their locations when Teresa was murdered via gunshot(s) to the head. Two bullet fragments were found in the garage and one of those bullets bore traces of Halbach's DNA. State crime lab firearms expert William Newhouse concluded that this bullet had been fired from a rifle found hanging over Avery’s bed. Newhouse linked ammunition found in Avery's desk drawers to this bullet fragment."
Regarding point 1, I have demonstrated with citations from the forensic literature that the substance was not bleach, nor was it a bleach-cleaned bloodstain. You have been told this repeatedly, and your response is to offer an insult instead of an explanation. And this was after you were called out for exaggerating the strength of the luminol reaction. Can you cite forensic evidence demonstrating that bleach and paint thinner were used? If you cannot, then it isn't worth discussing.

Regarding point three, The National Research Council's 2008 report Ballistic Imaging stated, “A significant amount of research would be needed to scientifically determine the degree to which firearms-related toolmarks are unique or even to quantitatively characterize the probability of uniqueness.”

The 2009 NAS Report “Strengthening Forensic Science: A Path Forward” concluded in part, “Toolmark and firearms analysis suffers from the same limitations discussed above for impression evidence. Because not enough is known about the variabilities among individual tools and guns, we are not able to specify how many points of similarity are necessary for a given level of confidence in the result. Sufficient studies have not been done to understand the reliability and repeatability of the methods.”

In 2011 Paul Giannelli wrote, "In a different passage, the [NAS] report remarked that “[m]uch forensic evidence ‘including, for example, bite marks and firearm and toolmark identifica- tions’ is introduced in criminal trials without any meaningful scientific validation, determination of error rates, or reliability testing to explain the lim- its of the discipline.” (Id. at 107-08.)"

In 2017 Sarah L. Cooper wrote, “However, overall, Strengthening concluded that ‘The scientific knowledge base for tool mark and firearms analysis is fairly limited.’” She went on to say, “The NAS [National Academy of Sciences] commented that ‘[t]his AFTE [association of firearms and tookmark examiners] document, which is the best guidance available for the field of tool mark identification, does not even consider, let alone address questions regarding variability, repeatability, or the number of correlations needed to achieve a given degree of confidence.’”

Thus Mr. Newhouse's claim of uniqueness is unscientific. Maybe someday the pro-guilt commenters will stop offering up rose fertilizer while claiming that it smells like roses.
It is possible both to be right about an issue and to take oneself a little too seriously, but I would rather be reminded of that by a friend than a foe. (a tip of the hat to Foolmewunz)

Last edited by Chris_Halkides; 21st November 2020 at 04:56 PM.
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