Firearms Testing & Tool Mark Examination

Our forensic scientists have the resources to analyze firearms at our laboratory in order to determine functionality as well as to generate test fires for the comparison of bullet and cartridge cases. Whether it is the reconstruction of an indoor crime that occurred within an enclosed bedroom or an outdoor drive-by shooting scene, we can assist in determining what most likely transpired at the scene and provide you with the decision-making information you need.

Firearm mechanism examination (function of firearms)

Our firearms examiners can examine and test the condition and functionality of firearms to determine if a weapon functioned properly during a case incident. We can also perform test firing of the firearm and generate exemplar bullets and casings for comparison or for issues regarding some aspects of shooting reconstruction such as distance determinations or ejection patterns.

Firearm serial number restoration

Manufacturers often stamp serial numbers onto products such as firearms, tools, cameras, watches and automobile parts. These numbers can establish ownership or manufacturer identity. Individuals may attempt to obliterate serial numbers by scratching, filing, grinding, over-stamping or welding new metal onto an obliterated area. Our scientists can restore punched or stamped obliterated serial numbers utilizing chemical procedures.

Cartridge case ejection

Semi-automatic and fully automatic firearms eject fired cartridge casings from the firearm during the normal course of operation. Our scientists can analyze the pattern of ejected cartridge casings to determine a range of the shooter’s location or weapon at the time of discharge.  This can add valuable information when performing shooting incident reconstructions.

Tool mark examination

A tool mark is an impression mark that results from contact with sufficient pressure between a tool and a surface. The tool mark examination process involves comparing the impressed or striated surfaces of the “tool” to the striated surface within the questioned tool mark. During this examination, our scientists can also examine for additional evidence such as hair, fiber, and fingerprint evidence.

Comparison of bullets, cartridge cases, and tool marks

During the normal functioning of a gun, numerous marks are left on the projectile and the cartridge case. Through the careful examination of the weapon, projectiles and cartridge cases, and exemplar projectiles and cartridge cases, our scientists can determine if the case projectiles and cartridge cases were shot from a suspected weapon.

Make and model determination

Make and model determinations are performed when fired bullets and/or cartridge cases are recovered from a scene, but no firearms are found.  The bullets and cartridge cases can be examined and the class characteristics of the markings can be categorized to generate a list of firearms that could have potentially fired the evidence.  This information can provide potential investigative leads.

GSR analysis

Gunshot Residue analysis, or GSR, is the detection of minute particles expelled by a firearm when it is fired. When the primer in a shell casing is ignited, a cloud of tiny particles, imperceptible to the naked eye, is expelled from the firearm. These minute particles are expelled primarily from the barrel of the gun but form a cloud emanating in all directions. An adhesive substance, typically a GSR Stub, is used to collect a sample from the hands or clothing of the suspected shooter. A scanning electron microscope (SEM) is subsequently used to analyze the surface of the stub for three common elements of gunshot residue – lead, barium and antimony.

At FACL, our firearms experts will work with you on any or all aspects of the process – collecting samples for GSR analysis, procuring GSR analysis of the evidence samples, and expert review of the GSR results. Each of our firearms experts have over 20 years of expertise in GSR sampling and interpretation and we can help you decide if GSR is right for your case and what the results mean if testing is done or has already been done.

Forensic trace evidence

Trace Evidence Analysis in forensics is the in-depth analysis of minute “traces” left behind at a crime scene or accident location. Most typically these traces are left when items touch or are rubbed together. However these trace materials were deposited, it is key to identify them, collect them, and then analyze them scientifically to determine their nature and their origin. Trace evidence analysis is a broad term. At FACL we have in-house expertise in bloodstain pattern analysis and GSR. We can also help you determine if other forms of trace analysis might benefit your case and coordinate with other labs to assist with other specific analyses. For instance, if our analysis of your case and evidence finds that there is trace evidence beyond the expertise and instrumentation in our laboratory, we can collaborate with an outside laboratory to perform and appropriately interpret the recovered material.

Toxicological/DUI report consultation

We can provide comprehensive toxicological consultation in cases involving either DUI (blood or breath samples) or DUI-Drugs (marijuana, illicit drugs, prescription medications, etc.). Toxicological consultation may also be applicable to other criminal cases where an individual may have been under the influence of alcohol and/or drugs, or suspicious death investigations requiring toxicological expertise and interpretation.