Firearms and Toolmarks

Service Manual   Table of Contents

The Firearms and Toolmark Section is dedicated to providing reliable scientific support to all law enforcement personnel. Services are provided at both the investigation and trial-preparation stages of criminal cases involving the use of a firearm or other tool.

The firearms and toolmark section is a versatile, well-equipped unit offering a number of services that can be useful to investigators. The section can determine:

  • The type of weapon that a particular bullet or cartridge case was fired from
  • Whether a bullet was, or was not fired from a suspected weapon
  • Whether a cartridge case was, or was not fired in a suspected weapon
  • Whether a tool found in a suspect’s possession was, or was not used to cut, scrape, pry, or pinch evidence material seized from a crime scene*
  • The original serial number of a weapon or other metal object after the number has been obliterated
  • If gunpowder is present on a victim’s clothing or on other evidence that may have been the target of the suspect
  • The distance from the muzzle of the firearm to the target at the time the weapon was fired**
  • If any elements are present in a properly prepared Gunshot Residue Kit that could be associated with the firing of a weapon
  • If fingernail clippings or fragments found at a scene can be identified as having come from a specific person
  • If a lamp was on or off at the time of an accident by examining the condition of the filament

*Tools found at the scene of a crime that cannot be associated with a suspect will not be examined.

**No muzzle-to-target distance tests can be done without the weapon that was involved in the shooting. Note: It cannot be determined “how long” it has been since a weapon was fired.

Many other miscellaneous examinations may be performed at the request of the customer. Examiners in the Firearms and Toolmarks section may conduct other testing that is of special interest to an investigator. Such requests may be made at the time of evidence submissions or by phone.

The following are general requirements for officers and other law enforcement personnel in collecting and submitting evidence to the Firearms and Toolmarks Section. As in all cases, common sense should be used when attempting to protect the integrity of evidence.

Firearms

Firearms should be collected carefully so that no parts of the gun are damaged. Officers should make sure that nothing comes in contact with either the inside of the barrel or the breech face, which is where the head of the cartridge rests before firing.

Weapons Recovered From Water (return to top)

Weapons removed from fresh water must be contained in the same water. Small lunch coolers work very well for handguns. In the event that a rifle or shotgun is removed from a lake or pond but can’t fit into a container, the weapon should be sprayed heavily with WD-40 or other lubricant and taken to the Firearms Section as soon as possible. The slightest bit of rust to the inside of the barrel will alter the individual characteristics necessary to make identification. If the gun is removed from the water, it must be oiled, making sure that the inside of the barrel is sprayed or filled with oil. This will slow the oxidation process. Weapons removed from salt water should be rinsed, heavily oiled and brought to the crime laboratory. Heavily bloodstained weapons should be packaged in bags with a biohazard label.

Protecting the Weapon from Damage (return to top)

Do not insert foreign objects into any part of the gun such as the barrel or ejection port. In the event the gun will be dusted for fingerprints or super glued, block both ends of the barrel gently with tape. This will prevent residue from building up inside of the barrel. If a loaded gun is submitted to the laboratory, you must notify DOFS personnel for instructions prior to submitting the weapon. Insure that the container is properly marked indicating that the firearm is loaded. Loaded firearms must be hand carried to the laboratory – do not leave in the lock box. Do not dry fire or work the action of any weapon that is to be submitted to the crime lab. Leaving empty cartridge cases in the chamber of a revolver when submitted might assist the examiner in determining from which chamber the round was fired.

Bullets, Cartridge Cases and Cartridges (return to top)

When bullets and cartridge cases are submitted for analysis, they should be individually packaged in their own canister, envelope, or other small container. Bullets (especially lead) should be lightly wrapped in tissue or cotton so that the bullet surface will be protected from possible damage.

  • Do not mark or engrave any surface on a bullet or cartridge case as this may damage individual characteristics. If evidence must be marked, mark the container itself.
  • Do not let any metal object such as forceps, knives or screwdrivers come into contact with a bullet. Metal objects will scratch the surface and alter the markings used for identification.
  • Numerous cartridge cases recovered from the same area may be packaged together in one container to save time and supplies.
  • Be sure to collect any wads or pellets in cases involving a shotgun. Many times a wad can be matched to the barrel of a shotgun, especially if it has a sawed-off barrel.
  • Film canisters or pillboxes make excellent containers for packaging bullets and cartridge cases.

Clothing (return to top)

Clothing submitted to the Firearms Section to be checked for gunpowder should be packaged in a paper bag or box. Do not package wet or bloody clothes until they have air-dried. Wet clothes will mold, making them difficult to examine. Inform the firearms examiner of how the layers of clothing were worn in order to assist in determining the path of the bullet. This information should be written on the evidence bag or the submission form. The Firearms Section also performs muzzle-to-target distance determinations. In order to perform this service, the gun identified as being used in the shooting must also be submitted. If no gun has been seized, the examination will be limited to a search for gunpowder or a gunpowder pattern.

Gunshot Residue Kits (return to top)

Gunshot residue kits should be processed as instructed in the kit and sealed with tape. The name of the person or object that was wiped should be written on the outside of the package so that there is no need for opening at the time of submission. Only GSR kits approved by the crime laboratory will be accepted. These are available directly from the manufacturer under agency contract number.

Tools for Toolmark Comparison (return to top)

The Firearms and Toolmark Section receives tools suspected of being associated with a crime scene. Cutting, pinching, prying, and striking tools are all examined by this section. Great care must be taken by the officer to protect the marking surfaces on the tool. If the entire tool cannot be wrapped, the tool’s marking surface should be protected using whatever materials are available to the officer. It should be understood that tools found at the crime scene that cannot link a person to the scene will not be examined. Materials recovered from the crime scene that are suspected of being marked by the recovered tool should be carefully removed from the scene so that the marks are not disrupted. Each item should be packaged separately and submitted to the laboratory.

Filaments (return to top)

When the service request is to determine whether or not a lamp was on at the time of an accident, the entire lamp must be brought to the crime lab whenever possible. Care should be taken not to disturb the filament inside the bulb so that it can be examined. The lamp should be packaged in a box so that it cannot move around inside the container. If the lamps have been destroyed, collect and submit as many fragments and pieces as possible.

Automobiles (return to top)

If it is necessary to have a firearms examiner examine a car or other vehicle associated with a shooting incident, the vehicle should be photographed and transported to the crime laboratory as soon as possible. Officers in charge must ensure that glass shattered or cracked by a projectile does not break further during the transport. Examining the glass fracture patterns can make valuable conclusions.

Integrated Ballistic Identification System (IBIS) (return to top)

The Integrated Ballistic Identification System (IBIS) is used to associate evidence in previously unsolved crimes. IBIS is a highly technical, computerized image analysis system that records striated images from bullets and cartridge cases and compares them to a national, and growing international, database of images. Bullets and cartridge cases recovered from victims and crime scenes are placed into the system and comparisons are made when agencies submit confiscated suspect weapons to the laboratory for testing. The images from the test fires are compared against the entire database. These images can be compared in a very few seconds, an impossible task for a firearms examiner using conventional procedures. These images are correlated by the IBIS system and given a score as to a possible match. The results of this correlation are called High Confidence Candidates, or HCCs. The firearms examiner makes a final determination to a positive match which then becomes a Hit. When a Hit has occurred, the involved law enforcement agencies are notified and they can then take the appropriate investigative and legal actions.