The Integrated Ballistics Identification System (IBIS) was created to expedite the highly labor-intensive and time-consuming task of matching ballistics information in police investigations. In addition to matching evidence from an ongoing or current investigation, IBIS can be used to link ballistic information to prior investigations and to guns used in crimes—that is, firearms that have been used in the commission of multiple crimes but that may not have been recovered in the investigation.
This technology was built and designed for forensic identification of ballistic information to firearms and is appropriate to use in any police department’s evidence or forensic unit.
Program Theory and Activities
Ammunition used in firearms has two distinct parts: 1) the bullet or projectile that leaves the barrel of a gun and strikes the intended target and 2) the cartridge that contains the gunpowder and propellant used to drive the projectile. When the trigger of a firearm is squeezed, this engages the firing pin to strike the rear of the cartridge, which ignites the gunpowder and propellant contained within. This explosion pushes the tip of the ammunition—the bullet—forward, separating it from the cartridge and propelling it down the length of the barrel.
Every firearm leaves unique identifying characteristics on the bullet and the cartridge during the firing process. The barrel of every firearm leaves lands, grooves, and specific marks, from the rifling—the winding pattern inside a barrel that spins the bullet to improve accuracy—on the bullet. The firing pin leaves marks on the rear of the cartridge as it is struck, and the breech face leaves ejection marks on the side of the spent cartridge casing. These microscopic marks are similar to fingerprints. Just as no two sets of fingerprints are alike, no two firearms are the same. For example, two identical 9mm pistols will not produce identical markings on the bullet and the casing. Hence, the ballistic information produced from these two pistols can be used to determine which gun was used in a crime and ideally link it to the offender who used it.
Traditional methods of matching ballistics information involve firearm forensic experts taking evidence collected from a single crime scene and searching through image databases and other evidence collections manually to select potential candidates until they find an exact match. The IBIS assists in the manual searching and identifying of potential candidate matches by automating the entire system and searching evidence of multiple crime scenes simultaneously. With every new image entered, IBIS compares the recovered evidence with existing images from prior crime scenes to identify possible matches. IBIS is able to search through volumes of existing images and prior evidence from crime scenes and suggests a small number of cases as potential matches. A firearm forensic expert then examines each potential match and makes the final determination of whether a match actually exists. IBIS is similar to an Internet search engine, in that it is a tool used to cull through vast amounts of information and the user makes the ultimate decision whether the search engine has produced the correct results.
IBIS is the software behind the Bureau of Alcohol, Tobacco, Firearms, and Explosives’ and the Federal Bureau of Investigation’s National Integrated Ballistics Information Network (NIBIN). The NIBIN was implemented in 2000. Within 3 years, IBIS technology had been used in 222 sites across the country and was responsible for 6,500 bullet-to-firearm matches.
In the pre–Integrated Ballistics Identification System (IBIS) period between 1990 and 1994 the average number of cold hits in a year was 8.8. During the first year of IBIS adoption and use, the number of cold hits rose dramatically—to 60 hits in 1995. This was due to the entering of backlogs of ballistics evidence into the system and IBIS software making comparisons. The number of cold hits decreased after the initial entering of backlogs and averaged out to 46 cold hits per year from 1996 through 2002. Regression results show a 6.23-fold increase in the monthly number of cold hits generated by the Boston Police Department’s Ballistics Unit after implementation of IBIS. This translates to 523 percent more cold hits per month. This analysis controlled for trends, seasonal variations, and the monthly number of crime guns entered into the system.