Detail Archives    Discuss This Issue    Subscribe to The Detail Fingerprint News Archive       Search Past Details

G o o d   M o r n i n g !
Monday, April 20, 2009

The purpose of the Detail is to help keep you informed of the current state of affairs in the latent print community, to provide an avenue to circulate original fingerprint-related articles, and to announce important events as they happen in our field.
Breaking NEWz you can UzE...

by Stephanie Potter

Lab split scuppers police
Malta Independent Online – Malta 04-18-09
Such examinations establish common authorship of latent prints found at the scene of crime with the ten-prints of a suspect and may also establish the ...

Dallas man arrested in nearly 23-year-old Fort Worth murder case
Star Telegram – Fort Worth,TX,USA 04-15-09
A national fingerprint database matched his prints to those found on duct tape that had been wrapped around the victim’s head. ...

Fingerprint unit fits right in at Pinellas County jail - St. Petersburg,FL,USA 04-17-09
But his fingerprints remained at the jail. During a subsequent computer search, a fingerprint technician made an intriguing discovery: The man's prints ...

Herrera guilty in woman's death
Bradenton Herald - FL, United States 04-17-09
Defense attorney Mike Reiter, representing Herrera, challenged evidence presented in the case including DNA, fingerprints found at Fore's home and ......

San Jose Police Department withheld inconsistencies in fingerprint ... – USA 04-18-09
Recent reports reveal that the San Jose Police Department has withheld fingerprint evidence in cases for years: when technicians disagreed whether a print ...

Recent CLPEX Posting Activity
Last Week's Board topics containing new posts
Moderated by Steve Everist and Charlie Parker

Public CLPEX Message Board
Moderated by Steve Everist


Updated the Detail Archives

Last week

Lori Haines and Eric Sahota brought us a report on the ASU conference in regards to the NAS report on Forensic Science.

This week

we see the first known mention of the NAS Committee Report in a publically-available motion to exclude document on impression evidence.


Motion to Exclude Firearms Identification Testimony





Criminal No. 2006 CFI 27899
Judge: Hon. Michael L. Rankin
Status Date: May 1st, 2009



Mr. Gayden hereby provides supplemental authority in support of his Motion to Exclude Firearms Identification Testimony (“Motion to Exclude”).

Mr. Gayden’s Motion, filed on October 6, 2008, citing the authority of the Due Process Clause of the Fifth Amendment and the rule set forth in Dyas v. United States, 376 A. 2d 827 (D.C. 1977) and Frye v. United States, 293 F.1013 (D.C. Cir. 1923), raised several objections to the anticipated testimony of firearms examiner Rosolyn Brown that tool marks on the ballistics evidence in this case “match” the recovered firearms “to a practical certainty” or “to a reasonable degree of scientific certainty,” among them:

* the fundamental assumptions of “uniqueness” and “reproducibility” of tool marks on ballistics evidence are not generally accepted in the relevant scientific community;

* the subjective methodology for identifying so-called “individual” characteristics is not generally accepted; and

* claims of identity should not be admitted because there is no generally accepted statistical expression for the probability of a coincidental match.

In support of his Motion, Mr. Gayden attached the affidavits of five eminent scientists from the relevant scientific community – a former FBI metallurgist, a mechanical engineer, two statisticians and a cognitive neuroscientist – as well as an affidavit from a scholar who has published extensively on the forensic identification sciences, and more specifically, on firearms and tool mark identification.1

In February of this year, the National Research Council (“NRC”) of the esteemed National Academy of Sciences (“NAS”) released a long-anticipated report entitled, Strengthening Forensic Science in the United States: A Path Forward (“NRC Forensic Science Report”)[…]. This report – the product of years of investigation by a committee composed of both “expert[s] in various forensic disciplines . . . [and] different fields of science [and] engineering” with the input of “countless experts” including “forensic science practitioners, heads of public and private laboratories, directors of medical examiner and coroner offices, scientists, scholars” – lends wholesale support to each of Mr. Gayden’s arguments to exclude firearm identification testimony. In sum, while “[t]he committee agree[d] that class characteristics are helpful in narrowing the pool of tools that may have left a distinctive mark,” they were adamant that the field of firearms comparison has yet to establish “the capacity to consistently and with a high degree of certainty support conclusions about ‘individualization.’”

Because the […] report constitutes a general and resounding rejection of firearms identification testimony by the relevant scientific community, and for the reasons set forth below and in Mr. Gayden’s Motion to Exclude, any testimony that markings on bullets and cartridge casings in this case were produced by particular firearms should be excluded from Mr. Gayden’s trial and, thus, Mr. Gayden’s Motion should be granted because it fails to meet the necessary standards for admissibility.

* * *

I. NRC Reports Are Given Significant Weight By Courts In This Jurisdiction As Well As By Forensic Practitioners

A. Porter and NRC I

B. Downfall of Comparative Bullet Lead Analysis

II. The NRC Forensic Science Report is the Work Product of the Relevant Scientific Community

A. Committee Members

B. Reviewers

C. Presenters

III. Firearms Identification Testimony Is Not Generally Accepted By The Relevant Scientific Community

A. The fundamental assumptions of “uniqueness” and “reproducibility” of tool marks on ballistics evidence are not generally accepted

B. The subjective methodology for identifying so-called “individual” characteristics is not generally accepted

1. It lacks a “precisely defined process”
2. No standard for minimum points of comparison
3. No consensus on the meaning of “match”
4. Unknown error rate
5. Subjective methodology heightens exposure to contextual bias

C. There is no generally accepted statistical expression for the probability of a coincidental match

* * *


Little more than a month has passed since the Committee publicized its finding that a “match” in the field of firearms and tool mark comparison has no scientific meaning or basis, and garners no general support in the relevant scientific community, and already the forensic community is responding. On April 3rd and 4th, 2009, forensic scientists and scholars from across the country convened in Tempe, Arizona to discuss the NAS Forensic Science Report at a conference entitled, Forensic Science for the 21st Century: The National Academy of Sciences Report and Beyond. Among the many panel members was Chris Hassell, the current director of the FBI Crime Laboratory. Mr. Hassell, representing an influential voice in the forensic sciences, noted that in light of the NRC Report the FBI’s firearms analysts will no longer testify to conclusions of individualization. Clearly the MPD’s firearms comparison practice is out of step with the current understanding of the limitations on the field if they are not following suit.

While the scientific community has rejected the notion that reliable individualization conclusions can presently be drawn from firearms tool mark evidence, its members are agle to agree “that class characteristics are helpful in narrowing the pool of tools that may have left a distinctive mark.” [2] Therefore, until claims of individuality by forensic firearm examiners are generally accepted in the scientific community, Ms. Brown should be limited by this Honorable Court to testifying, if at all, to only class similarities and should be precluded from offering opinions on individualization under the rule of Frye, Dyas and the Due Process Clause of the Fifth Amendment.


1. Throughout this motion, “firearms” comparisons and “tool marks” comparisons are used interchangeably. Firearms comparisons are a subset of tool mark analysis.

2. Classification opinions, too, must be backed by empirical evidence. While many of the problems discussed with respect to individualization conclusions – e.g. untested assumptions and unvalidated methodology – are also inherent in classification testimony, there is more of an empirical underpinning for the opinion that marks on a bullet are similar to those made by a model of gun.

Respectfully Submitted,
J. Christopher McKee, D.C. Bar 470107
Jospeh Caleb, D.C. Bar
Counsel for Willie Gayden
Public Defender Service

Delivered to Assistant US Attorney Steven Wasserman
April 8, 2009


Bookmark and Share


Feel free to pass The Detail along to other examiners for Fair Use.  This is a not-for-profit newsletter FOR latent print examiners, BY latent print examiners. The website is open for all to visit! 

If you have not yet signed up to receive the Weekly Detail in YOUR e-mail inbox, go ahead and join the list now so you don't miss out!  (To join this free e-mail newsletter, enter your name and e-mail address on the following page:  You will be sent a Confirmation e-mail... just click on the link in that e-mail, or paste it into an Internet Explorer address bar, and you are signed up!)  If you have problems receiving the Detail from a work e-mail address, there have been past issues with department e-mail filters considering the Detail as potential unsolicited e-mail.  Try subscribing from a home e-mail address or contact your IT department to allow e-mails from Topica.  Members may unsubscribe at any time.  If you have difficulties with the sign-up process or have been inadvertently removed from the list, e-mail me personally at and I will try to work things out.

Until next Monday morning, don't work too hard or too little.

Have a GREAT week!

View Archives