The Bureau of Alcohol, Tobacco, Firearms and Explosivesí
National Integrated Ballistic Information Network Program

Audit Report 05-30
June 2005
Office of the Inspector General

Appendix VIII

Process for Collecting and Entering Evidence into NIBIN,
Comparing the Evidence to Identify Potential Matches,
and Examining Potential Matches to Confirm Hits

Collecting and Entering Evidence

Evidence can be submitted for entry into NIBIN by either a NIBIN partner agency or from a participating law enforcement agency through a given partner agency. The ATF wants all crime-related bullets and cartridge casings collected at crime scenes, and all bullets and cartridge casings from test-fired firearms collected at crime scenes to be entered into NIBIN. The exceptions are evidence from .22 caliber firearms, firearms greater than .50 caliber, and shotguns, because the IBIS equipment is not capable of analyzing evidence from these types of firearms. During the audit, we determined the policies and procedures for the collection and entry of evidence into NIBIN varied among partner agencies. Therefore, the collecting and entering process described below is based on the protocol for ATF Laboratories, which is similar to the process used by the NIBIN partner agencies.

  • The evidence technician enters firearms and case information into the laboratory evidence tracking system when the evidence arrives at the laboratory. The items collected are compared to the evidence paperwork and transmittal. The containers are resealed and placed in a vault. A case jacket is produced with the case information.
  • In the case of a single submission, with a single firearm to be test-fired for NIBIN, the container is brought into the exam room along with the corresponding case jacket. Notes are made on the type and condition of the evidence containers, the general description of the firearm, make, serial number, type of actions, and other related information. The firearm and container are marked for identification. The date of occurrence is noted from the case information. The firearm is evaluated for safety and functionality. The description of the number and caliber of rounds of ammunition is noted. Test-fire ammunition and the component container are selected and appropriately marked for identification.
  • For safety reasons, the test-firing can only be performed with a witness. The firearm and ammunition are taken to the test-fire tank area; the firearm is loaded with no more than two rounds of ammunition; the firearm is test-fired; and the bullets and cartridge casings are retrieved.
  • Each of the test-fired bullets and cartridge casings are individually marked for identification, typically by scribing the base of the bullets and the side of the casings. The bullets are wrapped in tissue, and placed with the casings in the container. The evidence is then taken to the NIBIN entry area.
  • The cartridge casings are evaluated for ejector placement. The bullets are also evaluated for the number of land-engraved areas and direction of twist. The bullets are then prepared for NIBIN entry by hot-gluing the bullets to pegs that are mounted onto the RDAS microscope. The case information is entered into the IBIS equipment regarding the firearm and component identifiers.
  • The bullets and cartridge casings are repackaged and stored in a file system for any further examinations. The case file and notes are collected and a draft examination report is prepared. The report is peer reviewed, officially printed, and signed.
  • The evidence custodian prepares the evidence for return, and the final entries are made into the evidence custody computer. All evidence (e.g., firearms, bullets, or casings) is returned to the investigation officer, the property custodian, or the participating law enforcement agency. Firearms evidence, if entered into NIBIN, should be retained for future comparison if a hit is determined. In the event there is test-fired evidence generated by a given laboratory, it is retained in the laboratory indefinitely for future reference.

The types of cases that should be entered into NIBIN are those crimes that could be identified as “serial” in nature, such as homicides, attempted homicides, gang-type shootings, drug-related shootings, drive-by shootings, officer-involved shootings, robberies, and concealed-weapons offenses.

The process of entering firearms evidence into NIBIN is referred to as acquiring images. After the images are acquired, the next process involves comparing the images to identify potential matches and is called reviewing correlation images. The final process is examining the potential matches to identify hits and is called viewing results.

Comparing Evidence to Identify Potential Matches

After the firearms evidence is entered into NIBIN, the system can perform searches on a local, regional, or national basis to identify potential matches. In November 2003, the system was enhanced to track and compare ballistic images associated with crime firearms nationwide. Prior to the enhancement, the system could only track and compare images locally and regionally.

A local search is automatically performed by the system. Each time a correlation is requested, the system automatically searches within the partition location of the regional server that the partner’s IBIS equipment has been configured to search against.

Although regional and national searches can be performed, they must be manually selected. To perform a regional search, the requestor must designate where to search from a map of the NIBIN regions. The requestor is then presented with a list of all the partner agencies in that region, and can either search against all the partner agencies shown or de-select those partner agencies that the requestor does not want included in the search. To perform a national search, the requestor must repeat the regional search for each NIBIN region, as the system will not search all regions at once.

None of the searches result in a positive match of bullets or cartridge casings fired from the same weapon. Instead, the system produces high-confidence candidates that are similar. The IBIS equipment ranks a list of images based on their correlation results. If the images are similar, they likely represent images of ammunition components fired from the same firearm. After the system identifies the high-confidence candidates, the top matches must be reviewed by a firearms examiner to confirm whether an actual match has been identified.

Examining the Potential Matches to Identify Hits

To confirm the potential matches as a hit, the firearms examiner obtains the original evidence and compare the high-confidence candidates to the physical evidence. If the high-confidence candidates selected match the actual evidence, a hit is identified and marked in the system by the firearms technician. Once confirmed, the hit must be recorded in NIBIN for reference purposes. Once the hit is recorded, the reference case, and the image within the case file are displayed in red. If a hit occurs between two sites, the information is not transferred to the other site by the system. Rather, the other site must be notified to create the hit in its own database.

Other NIBIN linkages derived by investigative lead, hunches, or previously identified laboratory examinations are termed “warm hits” and should not be counted as hits. When there is an interagency hit, the agency initiating and confirming the microscopic comparison will be credited for the hit. For example, if “Agency A” discovers a high confidence candidate from “Agency B’s” evidence, “Agency A” requests the physical evidence for review and confirms whether the high-confidence candidate is an actual hit. “Agency A” is credited for the hit because it was initiated by “Agency A.” However, if “Agency A” determines a high-confidence candidate had previously been discovered as a hit or had been identified as a hit from previous investigations or leads, the high-confidence candidate is not marked in the system as a hit. When an interagency hit is confirmed, each involved agency should mark the hit in IBIS. Further, only the agency initiating and confirming the comparison should include the hit in its statistics reported to ATF’s NIBIN contractor. The NIBIN contractor reports the hit information to the NIBIN field coordinators, who report the information to NIBIN headquarters through an electronic reporting system known as the NIBIN case system.40


  1. In addition, hit information is reported to NIBIN headquarters to promote the NIBIN program, as well as to develop the “Hit of the Week” or “NIBIN Success Story” publications.

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