Department of Civil Service

Description:

The Firearms Unit is responsible for identifying, examining, and analyzing firearms and related expended ammunition components. Firearm examiners perform operability testing, microscopic comparison of fired evidence, Gunshot Residue (GSR) range determination, General Rifling Characteristics (GRC) determinations on expended projectiles, serial number restoration, and NIBIN Acquisition and Correlation. NIBIN (National Integrated Ballistics Information Network) is a national database of digital images of expended cartridge cases and shotshells. Submitted images captured and processed through the NIBIN server produces a list of potential associations to other images of evidence entered into the same database. A trained examiner reviews the list for similar images to potentially link multiple crime scenes. General Rifling Characteristics (GRC) determination makes use of characteristics found on fired bullets (i.e. rifling type, direction of twist, and number and width of rifling impression) to narrow down on potential firearms that could transfer the combination of features observed on a single bullet. Caliber determination uses measurable manufactured characteristics of the bullet, such as bullet diameter and weight, to determine the bore size of the firearm capable of firing such bullet through. Expended shotshell projectiles and wads, can also be analyzed using techniques in caliber determination to determine shot size and/or gauge.

Unlike NIBIN, caliber determination, and GRC determination, which are used for investigative leads, microscopic comparison is a confirmatory method that allows for an identification or elimination to be made--- with sufficient features to support the conclusion. The method uses the comparison microscope, an instrument that allows two items to be mounted separately but analyzed under the same optical system simultaneously. Complex microscopic features specific to a firearm, and transferred on to fired evidence, are analyzed by the Firearms Examiner to determine if two items were fired from the same firearm.

The NYSP Firearms Unit also performs chemical analysis; serial number restoration and gunshot residue range determination. Serial number restoration is performed when firearms are submitted with the defaced or obliterated serial number. Various chemical etchants are used to develop the serial number thus, allowing the firearm to be identified. Gunshot Residue (GSR) range determination uses various chemicals to detect specific elements/compounds known to expel from ammunition when fired. These residues are expelled in a pattern associated to a range of distances from which a firearm was fired from. Test shots producing residue patterns at known distances are analyzed and compared to establish a muzzle to target range.

Skills:

good writing skills

good research skills

hands-on lab experience

Internship Areas: Criminal Justice/Corrections, Investigations, Pharmaceutical, Scientific Research