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Forensic Technology Center of Excellence: Validation and Evaluation of Magneto-Optical Imaging Technology for Recovering Obliterated Serial Numbers in Firearms

NCJ Number
Date Published
August 2015
38 pages

This report describes the methodology and presents the findings of Phase II in the testing and evaluation of the capabilities of magnet-optical (MO) sensor technology in detecting and visualizing obliterated firearm serial numbers non-destructively and in real time.


Phase I of the testing used stock bar samples in determining that the MO sensor technology is capable of detecting and visualizing obliterated serial numbers non-destructively and in real time. It also found that sensor usage is limited to ferrous and paramagnetic metals and requires direct contact between the sensor and the metal (Luyendijk, 2014). In order to validate these findings, Phase II of the testing used actual firearms with obliterated serial numbers; and magnetic particle inspection (MPI) was included as the other obliterated serial recovery method, so as to obtain data from the same samples and compare results. The testing of MO sensor technology in detecting and imaging obliterated serial numbers for actual firearms concluded that this technology is suitable for use by firearm examiners in detecting and imaging obliterated serial numbers. It is fast, easy to learn and use, and requires little to no sample preparation. The method can be used as a stand-alone technique, although it is often used in combination with other serial-number recovery methods. In cases that use the MO sensor in combination with a destructive method, the MO sensor technology should be used first. It is similar to the MPI method and produces comparable performance results while being more efficient. MO sensor technology has potential application in other forensic disciplines n addition to firearm examination. 27 tables, 12 figures, a 17-item bibliography, and appended detailed descriptions of various components of testing methodology

Date Published: August 1, 2015