Investigations | Section 5.4


Fundamentals of Criminal Investigations

Adam J. McKee, Ph.D.


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Section 5.4: Firearms and Toolmarks

Packaging Firearms

Avoid altering any stain on the firearm. Firearms should be unloaded and placed in a safe condition at the point of collection. If the collector is unsure of the proper procedure, assistance should be sought from a competent source such as a firearms instructor, departmental armorer, or an on-site firearm examiner. Always follow your department regulations. Ship firearms and ammunition according to your Department and the U.S. Department of Transportation’s regulations. Do not cough, sneeze, or talk over any sample being collected or dried.

When photographing the firearm, include a scale and an identification label. Take one or more location photographs that depict the object where it was found in relationship to other evidence at the scene. Turn over the firearm, and photograph the other side if stains, serial number, or safety position is apparent on that side. If no serial number is present, mark the firearm with identifying data, such as your initials and the time and date on at least one component that cannot be removed. Also, place identifying data on removable component(s), such as cylinder, grips or ammunition magazine. When there is no serial number on the firearm due to the firearm’s age, or the removal or defacement of the number, mark the firearm on non-removable parts, such as the barrel and the frame. Photograph the firearm to capture any existing stains (such as blowback), the serial number, and the safety position.

Place the mark in a location that will not interfere with existing markings.  Label the firearm box or a container for the object with your identifying data, such as initials and identification number, the date and time, evidence number, location, and evidence description. Evidence number: Each piece of evidence must have a unique number or identifying data. This number should correspond to the placard next to the evidence.

The evidence description should include:  

  • Type of firearm Location of any stains on the firearm
  • Whether the stains are wet or dry
  • Location of the firearm

Label the container just before collecting an object, and seal the container immediately after collection. These actions help to protect the chain of custody. When handling the firearm, do not touch areas of the firearm where latent fingerprints are likely to be found (such as on smooth surfaces). Handle the firearm by touching only the areas that are checkered or knurled.

Revolvers

A revolver is defined as a repeating firearm that has a cylinder containing multiple chambers and at least one barrel for firing.

Mark the cylinder with your initials and the time and date. Put the mark in a location that will not interfere with existing markings. Mark the cylinder position. Document the condition of the firearm. Information needed includes:

  • Number of rounds in the chamber
  • Type and location of any stains
  • Serial number, make, model, and caliber

Protect the barrel, chamber, or other operating surfaces from contact with other objects.  Handle the firearm by touching only those areas that are unlikely to contain latent fingerprints, such as areas that are checkered or knurled.

Check your agency evidence submission policy. For firearms that will be analyzed by a trained firearms examiner, a particular agency may require or prefer alternative procedures for submission of evidence to their laboratory. Determine which way the cylinder turns. Cylinder turn can be either clockwise or counterclockwise, from the perspective of the shooter. Create a cylinder diagram like the one below:

On the diagram, assign a number to each chamber in the cylinder. The chamber below the hammer/firing pin is number one. From number 1, continue numbering chambers as you move around it in the direction that the chamber turns. The diagram should show the state of each chamber – whether it contains a live or spent cartridge case, or is empty. Document in your notes the type of projectiles/bullets contained in each chamber of the cylinder that you observe. It is important to note the type of projectile/bullet used because more than one type could be in use in the firearm at the same time; e.g., “Chamber one (1) contained .357 caliber “Acme full metal jacket.”

Firearms should be unloaded and placed in a safe condition at the point of collection. If the collector is unsure of the proper procedure, assistance should be sought from a competent source such as a firearms instructor, departmental armorer, or an on-site firearm examiner. Remove the cartridge or case from the chamber carefully to avoid disturbing any potential trace evidence or latent prints on it. Mark each cartridge or case with the related chamber number. When labeling the cartridge or case, make all marks in or near the mouth of the casing. Do not label a cartridge or case near the rim, head, or primer.

Mark each cartridge or case with the number of the chamber in which they were contained. The cartridge or case directly below the firing pin is in position number one. Start with number one and move in the direction of the cylinder rotation. Label the container into which you will place the ammunition with the same chamber number as you wrote on the cartridge or case. If necessary, wrap each object carefully so as to protect any potential trace evidence. Mark each chamber once you have marked the ammunition. On each side of the strap, mark the chamber with the number it was assigned when numbering cartridges and cases. Place the firearm, with available filled ammunition container(s), in the rigid box or container that you prepared for the firearm. If you are collecting multiple firearms, be sure to package each firearm and associated ammunition separately from other firearms. When the firearm is too large to fit into a container, securely attach an evidence tag to it. The evidence tag should include the following firearm information:

  • Caliber
  • Make
  • Model
  • Serial number

Place the diagram into the labeled container with the firearm and filled ammunition containers. Make a copy of the diagram for your notes before placing the original copy into the box. Close the container and seal the entire opening with evidence tape.

Write your initials and identification number and the date and time across the evidence tape seal. Consider the possible presence of bodily fluids, latent prints and trace evidence when handling the firearm or submitting it for processing.

Other Firearms

Document the identity of the firearm or the listed firearm’s markings. If no serial number exists, mark the firearm with your initials and the time and date on at least one part that cannot be removed. When the firearm has a bolt, mark the bolt with your initials and the time and date. Information needed includes:

  • The safety position: on or off
  • Existence of ammunition in the chamber
  • Type and location of any stains
  • Serial number, make, model, and caliber or gauge

Protect the barrel, slide, chamber, and other operating surfaces from contact with other objects. Handle the firearm by touching only those areas that are unlikely to contain latent fingerprints, such as areas that are checkered or knurled. Firearms should be unloaded and placed in a safe condition at the point of collection. If the collector is unsure of the proper procedure, assistance should be sought from a competent source such as a firearms instructor, departmental armorer, or an on-site firearm examiner.

If removing ammunition, mark each cartridge, case, shell, or magazine as it is removed from the firearm. Some departmental policies allow labels to be placed directly on a cartridge or case. When labeling the ammunition, make all marks near the mouth of the casing. Do not label ammunition near the rim, head, or primer. Mark each cartridge or case with the number of the chamber or position in the magazine in which they were contained, starting with number one, or use another schema that is consistent within your department for the way that the ammunition is stored in the firearm. Document, in your notes, the type of projectile/bullet that you observe in the chamber. It is important to note the type of projectile/bullet used; e.g., “Chamber contained .357 caliber Acme full metal jacket.”

Mark each magazine to note where cartridges, cases, or shells are found in it. On each side of the magazine, mark the position in which each numbered cartridge or shell is found. The mark should include the number assigned to the related cartridge, case, or shell. The number reflects the position in the magazine in which cartridge, case, or shell is found. Label a container into which you will place the ammunition with the same number as you wrote on the cartridge, case, shell, or magazine.

The label on the box or container should include the number of the position in the magazine in which cartridge or case was found. If necessary, wrap each object carefully so as to protect any trace evidence on it. When the firearm does not fit into a container, attach an evidence tag that describes the caliber, make, model, and serial number. The trigger guard is frequently the attachment point for the evidence tag.

Place the firearm and ammunition container(s) in the container that you prepared for the firearm. Close the container and seal the entire opening with evidence tape. Write your initials and identification number and the date and time across the evidence tape seal. Consider the possible presence of bodily fluids, latent prints, and other trace evidence when handling the firearm or submitting it for processing.

Embedded Ammunition

Gunshot residue and fingerprints are extremely fragile. Collect gunshot residue and fingerprints as soon as possible. When possible, collect the entire object in which the ammunition is embedded.

Always wear protective gear when handling objects that could cut or otherwise cause injury to you. Do not cough, sneeze, or talk over any sample being collected or dried. Documentation When photographing the object: Include a scale and an identification label. Take one or more location photographs that show the object where it was found. Show the relationship of the object to other evidence in the photograph. Use rods or strings to show ammunition entry and exit points. In your notes, document characteristics of the object in which the ammunition is embedded. Information need Location of ammunition in the object Type of ammunition, when possible Apparent entry angle Collect the object containing the embedded ammunition, when possible. If you were unable to collect the entire object, collect the embedded ammunition: Use available tools (hammer, chisel/screwdriver, forceps, hand saw, etc.) to carefully loosen and remove the ammunition.

Handle the ammunition carefully to avoid destroying marks on it. Pad the tips of the forceps, for example, to protect the extracted item from forceps marks. When fragments and other items related to the embedded ammunition are found in the object or fall from the object, collect them also. During collection, handle the object very carefully to avoid damaging evidence, or dislodging the embedded ammunition or any related residue.

Label a container for the object with your initials and identification number, the date and time, evidence number, location and evidence description. Evidence number: Each piece of evidence must have a unique number. This number should correspond to the placard next to the evidence. Evidence description: The evidence description includes: Type of object Color of object Type of ammunition, when possible Location of the ammunition in the object, including orientation to key object feature(s); e.g., “Bullet of unknown type in piece of unstained wood beam in garage next to washing machine.” Label the container just before collecting an object, and seal the container immediately after collection. Packaging Place the object in the labeled container. Seal the opening of the container with evidence tape. Write your initials and identification number, and the time and date across the evidence tape seal.

Fired Casings and Wads

Use a “druggist fold” to create bindles that will be used to hold cases and wads. Always use clean gloves when handling evidence. Do not cough, sneeze, or talk over any sample being collected or dried.

When photographing the object, include a scale and an identification label. Take one or more location photographs that show the object where it was found. Show the relationship of the object to other evidence in the photograph.  Label a container for the object with identifying data, such as your initials and identification number, the date and time, evidence number, location, and evidence description. Each piece of evidence must have a unique number. This number should correspond to the placard next to the evidence. The evidence description should include:

  • Type of case or wad
  • Type of weapon used
  • Location where the case or wad was found; e.g., “.357 caliber spent case found lying on the garage floor, beneath the stool.”

Label the container just before collecting an object, and seal the container immediately after collection. Pick up the case or wad carefully to avoid damaging or dislodging fingerprints or other evidence. Use tools available to carefully loosen and remove the case or wad when it is difficult to reach and to avoid damaging evidence.

Place the case or wad into the labeled envelope. When multiple cases or wads are collected from the same area, place each case or wad in a separate container. Each container must be individually labeled. Individual, labeled containers with cases found in the same area can be packaged together for transport. Wads should not be packaged with other ammunition or related objects. Close the container and seal the entire opening with evidence tape. Write your initials and identification number, and the date and time across the evidence tape seal.

Loose Unfired Ammunition

Photograph the ammunition and the location where it was found. When photographing the object: Include a scale and an identification label. Take one or more location photographs that show the object where it was found. Show the relationship of the object to other evidence in the photograph.

Label an envelope for the ammunition with your initials and identification number, the date and time, evidence number, location and evidence description. Each piece of evidence must have a unique number. This number should correspond to the placard next to the evidence. The evidence description includes:

  • Type of ammunition
  • Location of unspent ammunition
  • Orientation of ammunition relative to firearm or other point of interest, when possible; e.g., “Acme full metal jacket case for a .357 caliber revolver found on garage floor.”

Label the envelope just before collecting an object, and seal the envelope immediately after collection. Photograph the ammunition and the location where it was found. When photographing the object, Include a scale and an identification label.

Take one or more location photographs to depict the object where it was found in relationship to other evidence in the photograph. Pick up the ammunition carefully to avoid dislodging fingerprints or other evidence. Place the ammunition into the labeled container. Unless departmental regulations state otherwise, do not wrap the casing. Wrapping it could disturb evidence that has not already been collected.

Close the container and seal the entire opening with evidence tape. Write your initials and identification number and the date and time across the evidence tape seal. Collect and package any additional ammunition or related items. When multiple pieces of ammunition or related objects are found in an area, place each object in a separate container. Each container must be individually labeled. Those individual containers can then be packaged together for transport.

Tool Mark Evidence

A tool mark is any impression, scratch, gouge, cut, or abrasion made when a tool is brought into contact with an item, leaving an impression of the tool.  In some cases, tool mark identification may link a person to the tool used in the commission of a crime.

Begin by taking overall photos of the object containing the tool mark to show its nature and relationship to the scene.  Take a second set of photos that will show the tool mark specifically so that detail can be seen. (Note that as tool marks are three dimensional and photographs are two dimensional, examinations cannot be made from photos alone).

By far, the best method for comparison of tool marks is to secure the actual item containing the mark and submit it to the laboratory along with the suspected tool.  Care must be taken to protect the working area of the suspect tool by wrapping it in paper. Under no circumstances should the investigator attempt to fit the tool into the mark as it may destroy the very evidence that is to be examined by the expert.

In dealing with large articles or non-removable articles, the tool mark itself may be cut out of the object bearing it. If this is impossible, the investigator has the option of making a silicone cast to the tool mark. Silicone is recommended for this replica as it will reproduce the necessary detail for examination. Plaster of Paris is not recommended for this type of casting.

Silicone kits are commercially available and the individual kit instructions should be followed.   The investigator may press the strings of an identification tag into the edges of the casting material in a way that will not affect the cast itself. This tag can then be filled out With the proper identification data.

Photograph the impression before casting it. When making a cast, be prepared to act quickly and methodically. Time is often a critical factor in successfully making a cast. Always use clean gloves when handling evidence. Documentation Photograph the impression. When photographing the object: Include a scale and an identification label.

Make at least one photograph where the camera lens is perpendicular or “orthogonal” to the tool mark surface. Take one or more mid-range location photographs that depict the object where it was found. Show the relationship of the object to other evidence in the photograph. Label a container for the object with identifying data, such as your initials and identification number, the date and time, evidence number, location, and evidence description. Each piece of evidence must have a unique number. This number should correspond to the placard next to the evidence. The evidence description should include:

  • Type of item being cast
  • Location of the item being cast
  • Orientation of the item being cast; e.g. to the north, to a feature of the object with the impression on it, or to a nearby object.

Label the container just before collecting an object, and seal the container immediately after collection. Clean out loose material from the impression, when possible, without disturbing the impression. Never discard a cast, regardless of condition when removed from the impression. Be sure to save and submit all casts to the laboratory.

Close the container and seal the entire opening with evidence tape. Write your initials, identification number, and the date and time across the evidence tape seal. Make sure that the container is also labeled with a description of the item cast, appropriate identifying data, such as your initials and identification number, the date and time, location and, when possible, the evidence number. If the item with the tool mark is collected, it should be packaged separately from a suspect tool(s) to prevent any additional marks, impressions or other damage. Never place the suspected tool(s) into the impression.


Key Terms

 


References and Further Reading

Stevens, B. L. (2017).  Comprehensive Modernization of Firearm Discharge Residue Analysis; Advanced Analytical Techniques, Complexing Agents, and Tandem Mass Spectrometry.  Available: https://www.ncjrs.gov/pdffiles1/nij/grants/251195.pdf

 

Modification History

File Created:  05/02/2019

Last Modified:  05/22/2019

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This work is licensed under an Open Educational Resource-Quality Master Source (OER-QMS) License.

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