dimensional metrology ballistics: forensics infrastructure ted vorburger, guest researcher john...

Dimensional Metrology

Ballistics: Forensics Infrastructure

Ted Vorburger, Guest ResearcherJohn Song, T. Brian Renegar, Alan Zheng, Wei Chu,…

Surface and Microform Metrology GroupAlso MSEL, ITL

Martin Ols, Robert Thompson Bureau of Alcohol, Tobacco, Firearms, and

Explosives (ATF)

Supported by EEEL Office of Law Enforcement Standards (OLES)

Project Managers: Susan Ballou, Robert Thompson


Contents

• A Short History of Four Ballistics Related Projects

• Accomplishments• Highlights• Project Status, an Observation, and Future

Work


A Short History of Four Ballistics Related Projects

• ATF recognizes the need for physical standards to verify control of automated optical microscopes in crime labs and contacts NIST OLES about developing standard bullets (1997)– OLES contacts MSEL… and holds a meeting– Participants point to MEL’s Surface & Microform Metr. Gp. (SMM) – OLES contacts SMM – Standard Bullet Project Initiated

• Feasibility of National Ballistics Imaging Databases (NBID) becomes an issue (2003)– ATF contacts OLES and SMM– OSTP and NIJ contact OLES, OLES contacts SMM – NBID Feasibility Project initiated

• Standard Casings Project initiated (2006)• National Ballistics Imaging Comparison (NBIC) Project initiated

(2008)


Accomplishments

• NIST Standard Bullet Workshops held (2003, 2006)

• Standard Bullet released as SRM 2460 (2006)

• Report on NBID feasibility released (2007)• Two NBIC Workshops held (2008, 2009)• Concluding NBIC Workshop set for March 23


35 SRM 2460 Standard Bullets were Delivered in January 2007




Standard Reference Material (SRM) Bullets and Casings for Testing Ballistics Imaging

Systems

SRM 2460 Bullets,40 units fabricated by Diamond Turning

SRM 2461 Casings,about 175 units being fabricated by Electroforming (P. Rubert)


Reproducibility of Standard Bullet Surfaces

Signature A from virtual standardNo. 1 land

Signature B from #001 SRM standard bullet, No. 1 land

Correlation:CCFmax = 99.55%

Signature differenceDs = 0.92%


Casing Regions Inspected for Identifying Characteristics

Ejector Mark

Breech Face

Firing Pin


Reproducibility of Standard Casings#001 vs. #002, CCFmax = 99.29 %


cited heavily in National Academies Report (2008).

www.mel.nist.gov/div821/webdocs-13/NISTIR2007-7362.pdf

MEL Report (NISTIR 7362)


Conclusions of NISTIR 7362:•For four different types of marked regions,-firing pin impressions from new guns,-firing pin impressions from used guns,-breech face impressions from new guns, -breech face impressions from used guns, surface topography analysis was more accurate for identifying matching casings than the optical microscopy technology in common use.

•However, the reproducibility of the surface topography was not high enough to be consistent with the accuracy requirements of a national database of new firearms


Ideal Case –All Guns Distinguishable Graphical Approach

Ref

eren

ce C

asin

g

Compared CasingACCFmax

James Yen, ITL


NBIDE Breech Face Impressions

NIST Topography IBIS Microscopy


National Ballistics Imaging Comparison• Objective: To establish quality control procedures for automated

ballistics inspections in crime labs and develop traceability to the ATF’s “Golden Images” of NIST’s Standard Bullets and Casings

• 19 Participants in 13 crime labs performing image acquisitions of Standard Bullets and Casings

• Data from all participants have been received.• Example : Scores of correlations of five NBIC participants’

images to ATF “Golden Images” of Standard Bullets over 13 months


Project Status, an Observation,and Future Work• All data for the NBIC Project have been received from the

participants and are currently being analyzed in collaboration with the Statistical Engineering Division, ITL

• The Third (and final) NBIC Workshop will be held on March 23 in St. Louis with the objective to draft and refine a quality control procedure for data acquisitions of standard bullets and casings.

• We have received, measured, and qualified 71 Standard Casings and are expecting the last shipment of 104 in March.

• We aim to certify and release SRM 2461 in FY09. • Scientific impact:These projects enabled us to show that careful

surface topography measurements with optical methods can correlate very closely with stylus methods.

• Based on the impressive reproducibility of electroformed standard casings, a new OLES project has been initiated in SMM/ PED/ MEL: “Toolmark Identification Proficiency & Validation Test Using Electroformed Replicas.”

dimensional metrology ballistics: forensics infrastructure ted vorburger, guest researcher john...

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