Gunshot Residue Test Results

Gunshot residue test results can be divided into three categories.

1. Those where a pattern of residues is found on the evidence garment and the questioned firearm and ammunition are recovered.

2. Those where a pattern of residues is found on the evidence garment and the firearm and ammunition are not recovered.

3. Those where only trace amounts or no residues are found on the evidence garment.

When a pattern of gunshot residues is found on a submitted article of clothing and the questioned firearm and ammunition are known, firearm examiners will try to bracket the muzzle-to-garment test results within a minimum and a maximum distance.  Results may read something like:

Exhibit 1 (victim's shirt) was examined and a pattered deposit of gunshot residues was found around a bullet entrance hole located in the shirt's left shoulder.  Exhibit 2 (firearm) was found to produce similar deposits of gunshot residues when fired at a target from a minimum distance of 6 inches out to a maximum distance of 18 inches.  

Bracketing the muzzle-to-garment distance within a minimum and maximum distance is being pretty specific.  To get a report back saying something like that listed above the exact firearm and ammunition used in the case must be known and there must be a significant pattern of nitrite residues on the garment.

The image on the left below shows a shirt from a case that has a bullet entrance hole in the front chest.  It has been processed for nitrite and lead residues.  The image on the right below shows the results of the Griess Test and the pink seen on the shirt is a very heavy deposit of lead residue.  Click on the images to see a larger view.

Below are the results of three Griess Tests standards, made at 3, 12, and 18 inches.  By comparing the Griess Test results from the evidence to the standards you can see that the 3-inch standard shows a nitrite deposit considerably more concentrated and smaller in diameter than the evidence pattern.  In addition, the 18-inch Griess Test standard shows a broader and less concentrated pattern than that seen on the evidence pattern.  The 12-inch Griess Test standard is very similar to that seen on the evidence pattern.

The muzzle-to-garment distance would then be reported as greater than 3 inches but less than 18 inches.

To somewhat confirm what the Griess Test results have shown the lead residue deposits on the evidence will be compared to the lead residues found on the standards.

Below are the actual target standards showing the lead residues present.  Again, the lead residues seen on the 3-inch target (left) are more compact and concentrated than those seen on the evidence shirt.  This confirms the 3-inch minimum distance.  The 18-inch standard (right) shows very little lead residue and again confirms the maximum muzzle-to-garment distance.  The 12-inch standard (middle) seems a little less concentrated than the lead deposit seen on the evidence shirt.

When a firearm is not recovered there still may be certain general conclusions that can be reached when gunshot residues are found on the evidence garment.

Contact or Near Contact Gunshot

Probably the easiest conclusion to report would be one involving a contact or near contact gunshot.  The results may read something like:

Exhibit 1 (shirt) was found to have a bullet entrance hole in the chest area that displays physical effects and gunshot residues consistent with a contact or near contact gunshot.

A contact or near contact gunshot will normally deposit a very intense ring of residue right around the margins of the bullet hole.

Higher velocity firearms can rip and tear clothing, like that seen in the image above, and the heat and flame from the burning gunpowder can melt synthetic fibers.

Close Range Gunshot

Another conclusion that is fairly easy to reach involves what can be call a close range gunshot.  The results may read something like:

Exhibit 1 (shirt) was found to have a bullet entrance hole in the chest area.  A heavy deposit of gunshot residues were found around this hole that are consistent with those that would be deposited by a close range gunshot.

Close range gunshots will usually leave a very concentrated deposit of residue around the bullet entrance hole that is visible to the eye.

A close range gunshot, like the one seen above, will typically be in the near contact to approximately 12-inch range of fire.

Intermediate Range Gunshot

An intermediate range gunshot usually will deposit a significant amount of particulate residue that is not easily seen with the eye but can be detected through a microscopic examination and through chemical testing. The results may read something like:

Exhibit 1 (shirt) was found to have a bullet entrance hole in the chest area.  A deposit of gunshot residues were found around this hole that are consistent with those that would be deposited by an intermediate range gunshot.

An intermediate range gunshot, like that seen in the above image, can range from just beyond the 12-inch range out to 24 to 36 inches. This depends greatly upon the caliber, barrel length and powder type used in the ammunition.

When no residues are found around a bullet hole, it can mean several things.

1. The firearm was at a distance far enough away that the residues did not reach the garment.

2. An intervening object between the firearm and garment preventing the residues from reaching the garment.

3. Gunshot residues were removed through severe handling, heavy bleeding, or by some other means.

There will also be times when only trace deposits of gunshot residues are found.  Trace amounts of gunshot residues can come from any number of sources.  Prior handling or firing of a firearm or being near a firearm that was discharged are just a couple possible sources.

When firearm examiners are presented with any one of these situations, they will generally report that no muzzle-to-target distance could be determined.

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