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Ballistic Imaging APPENDIXES
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Ballistic Imaging Appendix A Gun Enforcement and Ballistic Imaging Technology in Boston Anthony A. Braga* In March 1995 Boston was one of the first major cities to receive Integrated Ballistics Identification System (IBIS) ballistic imaging technology from the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF). The system was considered fully implemented when the Boston Police Department (BPD) ballistics unit made its first IBIS match in July 1995 (Braga and Pierce, 2004). Prior to the adoption of IBIS, BPD ballistics operations usually consisted of manually matched bullets and cartridge casings recovered at a crime scene to determine whether the bullets or casings were fired from a suspect’s firearm. Firearms examiners in the ballistics unit did not systematically compare bullets and casings from one scene to ballistics evidence recovered at other crime scenes to determine whether separate gun crimes were linked. When BPD firearms examiners did attempt to make such matches, known as making “cold hits,” it happened in one of * Program in Criminal Justice Policy and Management, John F. Kennedy School of Government, Harvard University. This research was supported by funds from a number of sources, including the National Research Council, the National Institute of Justice, Forensic Technology WAI, Inc., and the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF). The author would like to thank the members of the committee for their helpful comments and suggestions on this work. Thanks are also due to Special Agent Terrence Austin (retired), former director of the ATF National Tracing Center; Marianne Hinkle, former Assistant U.S. Attorney, District of Massachusetts; Assistant District Attorney Raffi Yessarian of the Suffolk County (MA) District Attorney’s Office; and Commissioner Kathleen O’Toole, Superintendent Paul Joyce, Deputy Superintendent Paul Fitzgerald, Deputy Superintendent William Casey, Sergeant James O’Shea, Sergeant Kathy Doherty, Sergeant Mark Vickers, Sergeant John Daley, Detective Earl Perkins, and Carl Walter of the Boston Police Department.
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Ballistic Imaging two ways: (1) the firearms examiner may have recognized some unique markings on a cartridge casing as very similar to markings on a cartridge casing recovered at another crime scene; (2) a detective would develop an investigative lead from a confidential informant that a recovered crime gun had been used previously in another gun crime and request the firearms examiner to make comparisons of evidence across the crime scenes (Braga and Pierce, 2004). Since adopting the IBIS technology, it has become BPD policy to test fire all recovered crime guns, and the expended bullets and cartridge casings are imaged and entered into the IBIS database (Braga and Pierce, 2004). Importantly, the BPD makes an aggressive effort to collect, image, and enter ballistics evidence from all incidents involving firearms—ranging from homicides to illegal possession cases to suicides—into the IBIS database. Only noncrime guns that are held by the BPD for safekeeping are not imaged. The BPD refers to this process as comprehensive imaging of all crime-related ballistics evidence. In sharp contrast, in the pre-IBIS period, cartridges or bullets from different crimes scenes were cross-examined by firearms examiners only in extreme circumstances or when there was a suspicion two criminal events were connected. As of December 31, 2003, the BPD ballistics unit had entered some 2,400 bullets and 12,700 cartridge casings into its imaging database and had recorded 412 confirmed IBIS-related matches.1 THE USE OF IBIS MATCHES IN GUN VIOLENCE PREVENTION STRATEGIES Confirmed IBIS matches are a key part of the BPD’s gun violence reduction strategy, the Street Violence Suppression Project (SVSP).2 Every 2 weeks, the Boston Police convene an interagency working group comprised of BPD officers and detectives, ATF agents, assistant U.S. attorneys, assistant Suffolk County district attorneys, Massachusetts State Police, Massachusetts probation officers, Department of Youth Services (juvenile corrections) case workers, and other criminal justice practitioners as 1 The original study reported 396 matches made through the first week of December 2003 (Braga and Pierce, 2004). The BPD ballistics unit has been imaging ballistics evidence for other local police departments that share gun crime problems with Boston (Braga and Pierce, 2004). For example, there are strong street gang connections between Boston and the communities of Brockton (MA), New Bedford (MA), and Providence (RI) and gang-involved gun criminals tend to travel between the cities. 2 The SVSP was the latest incarnation of the Boston Police Department’s evolving strategic response to gun violence among serious offenders. Earlier versions of BPD strategic violence prevention initiatives include Operation Ceasefire (Kennedy et al., 1996; Braga et al., 2001), which was in place between 1996 and 2000, and the Unsolved Shootings and Impact Player Assessment Project, which was in place between 2001 and 2004 (Braga and Pierce, 2004). As of January 2007, the same process is now part of the BPD Compstat process.
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Ballistic Imaging needed. This meeting serves as a scanning and analysis forum for ongoing conflicts among violent gangs and other gun incidents with high potential for retaliation. After specific violence problems are identified, BPD officers and detectives are assigned responsibility for devising and implementing appropriate violence prevention plans to halt outbreaks of violence. Strategies are developed at a separate response development meeting; however, implemented plans and progress updates are presented at the bi-weekly meetings to disseminate knowledge on what works (and what doesn’t) and to hold officers responsible for keeping targeted groups and individuals from shooting at each other. At the SVSP scanning and analysis meetings, BPD crime analysts and intelligence officers present information on gun incidents over the previous 2 weeks. Recent IBIS matches are highlighted at the beginning of each meeting. Members of the working group discuss the circumstances associated with the linked incidents; information developed through interviews with arrested offenders, victims, and witnesses; available intelligence on current “beefs” between gangs or the activities of serious violent offenders in the linked areas and analyses of other physical evidence collected at the crime scenes, such as DNA and fingerprints. If guns are recovered and successfully traced by ATF, information on the first retail purchaser and licensed dealer are presented. In essence, an “information chain” is constructed around the events linked by ballistics evidence. The amount and types of information associated with linked gun crime events can vary tremendously across matches; see Figure A-1. All matches provide investigators with the caliber, crime types, dates, times, and locations of shots fired from a particular gun or from a recovered gun that is subsequently test fired by BPD firearms examiners. However, other key information that may be critical to solving a particular violent crime may or may not be available to investigators, depending on the nature of the incidents linked by ballistics evidence. To understand what happened at a crime scene, investigators have to rely on information provided by witnesses, victims, and arrested offenders. Whether these individuals are present varies across crime scenes. When they are present, the information provided may or may not be very helpful to an investigator for a wide variety of reasons. Witnesses and victims may not know the identity of the assailant(s). Witnesses may not want to share information with law enforcement agents because they fear reprisals. Victims may be active criminals who prefer street justice for their assailant(s) to the slow justice of the legal system. To avoid self-incrimination, arrested offenders may not provide investigators with any useful information. The presence of other physical evidence, such as DNA and fingerprints, and law enforcement intelligence on violent criminals feuding in the affected areas will also vary across crime scenes.
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Ballistic Imaging FIGURE A-1 Types of investigative information linked by IBIS-suggested matches. While ballistic imaging makes an important investigative link between two gun crime events, the availability of key information that may be critical to resolving crimes depends on random situational characteristics of the linked events. An IBIS-suggested match that links cartridge casings from shots fired from two locations with no witnesses, victims, or suspects to interview and no other physical evidence left at the scenes has low immediate potential for making arrests. An IBIS-suggested match that links a gun assault with victims and witnesses willing to talk, to a gun possession case, in which a gun is recovered and an offender is arrested, is much more likely to generate an arrest for the first gun crime. However, while more evidence is available to investigators, arrests and successful prosecutions are not guaranteed. Leads from ballistic imaging link guns—not individuals—to
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Ballistic Imaging crime scenes. In linked guns, a different person could have committed the first crime. For example, the first actual shooter may have subsequently sold the gun to an unidentifiable street drug dealer who then sold it to the illegal possessor apprehended in the second crime. The resulting information chains that are constructed around gun events have value to law enforcement officials in two ways: (1) holding offenders accountable for their crimes and (2) guiding violence prevention efforts on risky groups and individuals. Obviously, law enforcement agents want to arrest violent gun offenders; making links across events can generate important leads that may result in the apprehension and prosecution of gun criminals. However, IBIS-suggested matches also provide important opportunities for Boston law enforcement agencies to better understand and respond to street violence. The links help guide violence prevention efforts by establishing patterns of violence in particular areas and among specific individuals. Even matches that have little immediate potential for generating an arrest can have strategic value in understanding and responding to violent crime problems. For example, a match between two “shots fired” incidents with no victims, arrested offenders, and witnesses can be coupled with intelligence on active conflicts among groups in the places linked by shell casings fired by the same gun. The link serves as an early warning sign that repeat shots are being fired in a particular gang turf area. Based on this pattern, the interagency working group focuses resources on gathering additional intelligence on conflicts in the area and immediately increases their presence in the area to prevent additional violence. ASSESSING THE VALUE ADDED TO BOSTON GUN LAW ENFORCEMENT OPERATIONS BY BALLISTIC IMAGING TECHNOLOGY Assessment of Changes in the Productivity of the BPD Ballistics Unit To measure the effect of ballistic imaging technology on the productivity of the BPD ballistics unit, it is important to consider the nature of the technological innovation and its potential impact on BPD operations. IBIS is able to cross-examine large volumes of evidence and suggests a small number of candidate cases that may match the evidence in question. The firearms examiner then carefully looks at the candidate cases using standard procedures to determine whether a match actually exists. The nature of a confirmed match and its utility to a criminal investigation does not change as a result of the IBIS technology (Braga and Pierce, 2004). As mentioned above, forensic evidence, such as ballistics matches, is one part of an information chain (such as eyewitness testimony, circumstantial evidence, etc.)
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Ballistic Imaging that leads to the ultimate arrest and prosecution of gun criminals. Arrest and prosecution is influenced by many factors beyond the forensic link of a particular gun to ballistics evidence collected at separate crime scenes. Since the value of a ballistics match to the resolution of a crime is not meaningfully different before and after the adoption of the IBIS technology, the outcome of interest is the number of matches made by the ballistics unit, not the ultimate disposition of the resulting cases. As such, Braga and Pierce (2004) examined whether IBIS changed the ability of the BPD ballistics unit to link gun crimes. To determine whether the adoption of the ballistic imaging technology was associated with a change in productivity, the annual and monthly number of cold hits made by the BPD ballistics unit was computed for the 14-year time period between 1990 and 2003.3 Figure A-2 presents the yearly number of cold hit ballistics matches made by the BPD ballistics unit during the study period. During the pre-IBIS period of 1990–1994, the ballistics unit made an average of 8.8 cold hits per year. After the adoption of IBIS, the productivity of the BPD ballistics unit rose dramatically to 60 cold hits in 1995 as the unit immediately entered a large backlog of ballistics evidence into the system. The yearly number of hits decreased during the 1996–1998 period; then, as the inventory of casings in the system grew, it increased again between 1999 and 2003. The ballistics unit moved to new BPD headquarters in 1998; the move limited the use of the IBIS equipment for about 2 months and was associated with the low number of matches (25) in 1998. Nonetheless, the BPD ballistics unit averaged 45.7 cold hits per year between 1995 and 2003. The Braga and Pierce (2004) analysis of the impact on the monthly number of cold hits made by the BPD ballistics unit associated with the adoption of the IBIS technology followed a basic one-group interrupted time-series design. Of course, it would have been ideal to have a control group that did not receive the IBIS technology to make comparisons. However, given the ATF’s National Integrated Ballistic Information Network (NIBIN) program, there is no major city comparable to Boston that has a ballistics unit without ballistic imaging technology. In addition, among major cities, Boston showed some of the most dramatic declines in firearms crime (Braga et al., 2001); see Figure A-3.4 Consequently, it was also difficult to find an appropriate control city or group. In absence of a separate control group, the key to a compelling one-group interrupted time-series 3 The findings reported here simply add an additional year of data to the original Braga and Pierce (2004) study that examined ballistics matches between 1990 and 2002. 4 The adoption of IBIS was not associated with the drop in gun violence in Boston. Rather, a focused deterrence strategy designed to keep gangs from continuing their cycles of ongoing violence was found to be associated with the significant decrease in Boston youth gun violence (Braga et al., 2001).
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Ballistic Imaging FIGURE A-2 Boston Police Department ballistics matches, 1990–2003. FIGURE A-3 Serious gun crime incidents in Boston, 1990–2003. NOTE: Serious gun crime incidents are defined as gun-related homicides, aggravated assaults, and robberies.
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Ballistic Imaging design is the degree to which other forces not related to the intervention influence the outcome variable. If at the time the IBIS technology was introduced in Boston the staff of the ballistics unit also changed, this could pose a problem of a change in “instrumentation” (Campbell and Stanley, 1966; Cook and Campbell, 1979). However, this was not the case in Boston. As Table A-1 shows, the ballistics unit staffing level of BPD firearms examiners remained the same before and after the IBIS technology was adopted; see the period from 1993 to 1997. For the entire 10-year period, the unit had, on average, 6 firearms examiners and 10 total personnel on staff. There was a slight decrease in the number of firearms examiners and a corresponding increase in support staff, but the only substantive change in the dynamics of the ballistics unit was the addition of the IBIS technology (Braga and Pierce, 2004). For an empirical analysis of trends in BPD ballistics matches, July 1995, the month of the first IBIS cold hit match, was selected as the date the IBIS technology was fully implemented (Braga and Pierce, 2004). The pre-IBIS time series was comprised of the monthly counts between January 1990 and June 1995; the post-IBIS time series was comprised of monthly counts between July 1995 and December 2003. A binary dummy variable indicating whether the IBIS technology was present or not was constructed to estimate the effects of the intervention on the monthly counts of cold hits. Negative binomial regression models, controlling for the monthly count of gun crimes, seasonal variations as measured by monthly dummy variables, and simple linear and nonlinear trends, revealed that the adoption TABLE A-1 Staffing Levels of the Boston Police Department Ballistics Unit, 1993–2003 Year Supervisors Firearms Examiners Support Staff Total 1993 1 7 1 9 1994 1 7 1 9 1995 1 7 1 9 1996 2 7 1 10 1997 2 6 2 10 1998 2 5 3 10 1999 2 6 3 11 2000 2 5 3 10 2001 2 5 3 10 2002 1 4 4 9 2003 1 5 5 11
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Ballistic Imaging of IBIS was associated with a statistically significant six-fold increase in the monthly number of hits generated by the BPD ballistics unit.5 Some observers suggest that ability of IBIS technology to make links across crime scenes can be easily undermined by criminal offenders. These critics suggest that ballistic imaging technology is limited because determined criminals can alter markings on or replace barrels, slides, extractors, and firing pins. These modifications would alter the telltale markings on ballistics evidence and prevent matches from being made (see, e.g., Kopel and Burnett, 2003). Unfortunately, data are not available to determine whether criminals are modifying their firearms to avoid detection. However, if criminals are seeking to avoid detection, they can simply switch from semiautomatic pistols to revolvers because the latter are less likely to leave cartridge casings at a scene when fired. The available evidence suggests that Boston gun criminals are not switching guns to avoid detection: As Figure A-4 shows, there was no substantive change in the proportions of semiautomatic pistols and revolvers in handguns recovered by the Boston Police after the adoption of IBIS in 1995. Extended Analyses of Boston IBIS Matches The Boston Police Department’s Unsolved Shootings Project and Impact Player Assessment meetings held between October 2001 and July 2004 generated detailed data on gun crime incidents and gun criminals involved in IBIS matches. A total of 104 sets of ballistics matches involving 244 distinct gun crimes were made over the course of this initiative.6 The number of incidents in each set of matches ranged from 2 gun crimes to 6 gun crimes with a mean of 2.3 gun crimes per set. The amount of time between the first incident and the last incident in a set of ballistics matches ranged from a few hours to 34 months, with a mean of 6 months. Five calibers, all of which are commonly used in semiautomatic pistols, accounted for 93 percent of the crime guns used in these 104 sets of IBIS matches. The five most frequently matched calibers were 9mm (39 percent), .38 (21 percent), .40 (12 percent), .45 (11 percent), and .25 (10 percent). The 244 gun crime incidents included in the 104 sets of matches mostly involved gun assaults 5 In this updated analysis, the findings are essentially unchanged from the original (see Braga and Pierce, 2004) study. The key coefficients in the updated negative binomial regression model were IRR = 6.0988, Robust SE = 2.4723, Z = 4.46, P>|Z| = 0.000, and log likelilhood = −314.0913. 6 The term “set of matches” is used to distinguish the matches discussed here from those discussed above: A set of matches involves all hits (or matches) generated by the same gun across multiple crime scenes; a match, as used above, simply is a hit based on new evidence entered into IBIS.
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Ballistic Imaging FIGURE A-4 Recovered handguns in Boston, 1991–2003. (43 percent), shots fired (30 percent), and illegal gun possession (13.5 percent) cases; see Table A-2. An arrest was associated with 51 percent of the match sets (53 of 104) resulting in 87 individuals arrested. An analysis of the timing of the arrests suggests a complex investigative process. In 52.8 percent of the match sets, the arrest and the last incident coincided. In these cases, the arrest of the gun offender(s) seemed to end the chain of violent events that was associated with a particular crime gun. In 32.1 percent of the match sets, an arrest was made after the last incident. This time lag suggests that additional investigative work led to the identification and eventual apprehension of the gun criminal(s) involved in a string of incidents using the same gun. At least one additional gun crime was committed with the same gun after an offender was arrested in 15.1 percent of the sets of matches. This situation suggests that, although an offender was apprehended, the crime gun was still on the street and being used in subsequent crimes. As described above, IBIS matches do not change the inherent value of ballistics evidence in an investigation because many other factors help determine whether an arrest is eventually made. An IBIS match does not guarantee an immediate arrest. For instance, the linked incidents may not involve victims or witnesses that can or are willing to make a positive iden-
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Ballistic Imaging TABLE A-2 Crime Types in 104 Sets of Boston IBIS-Suggested Matches Crime Type Number Percent Gun assault 104 42.6 Shots fired 72 29.5 Illegal gun possession 33 13.5 Gun homicide 17 7.0 Warrant (search/arrest) 13 7.0 Found gun 4 1.6 Gun robbery 1 0.4 tification. Rather, matches better position law enforcement agents to identify gun criminals through strategic analyses of information and intelligence sharing. The Boston Police and their criminal justice partners use the IBIS information as a tool to shed light on the dynamics at play in violent street social networks and further their ability to apprehend violent gun criminals. IBIS provides Boston investigators with more opportunities to make links among individuals and locations through a particular gun. The IBIS matches were associated with the arrest of very serious gun offenders that were well known to the criminal justice system. Of the 87 arrested gun offenders associated with the IBIS matches, 93 percent were male, and they ranged in age from 13 to 51 years, with a mean of 22 years of age. When the names and birth dates of these arrest individuals were run through Massachusetts state criminal history systems, 92 percent had been arraigned at least once in Massachusetts courts prior to their current arrest. Of these known offenders, 59 percent were previously convicted felons and, after their personal information was run through the BPD intelligence database system, 42 percent were known gang members. Of the known offenders, they had a mean of 10 prior arraignments for a wide variety of criminal offenses: 63 percent had at least one prior armed violent crime arraignment, 51 percent had at least one prior unarmed violent arraignment, 36 percent had at least one prior nonviolent gun crime arraignment, 60 percent had at least one prior drug crime arraignment, 75 percent had at least one prior property crime arraignment, and 75 percent had at least one prior disorder crime arraignment. These gun offenders were also extensively involved with the criminal justice system before their immediate arrest. Of the previously known offenders, 48 percent were on active probation when they were arrested, 83 percent were on probation prior to their arrest, 64 percent had been committed to a secure adult or juvenile correctional facility prior to their arrest, and 15 percent had been subjected to a restraining order before their arrest.
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Ballistic Imaging High conviction rates for fully adjudicated gun offenders were also associated with the IBIS matches. It is important to note again that IBIS matches do not guarantee or necessarily generate a conviction. Rather, in Boston, IBIS data are one part of an aggressive investigative process that is highly focused on sharing information and analyzing data to apprehend violent gun offenders. As such, the higher conviction rates should be credited to the overall law enforcement initiative rather than simply being credited to IBIS matches. In November 2004, 58.6 percent of the arrested offenders were fully adjudicated, 34.5 percent were still engaged in the trial process, and 6.9 percent were not charged for their crimes. Of the fully adjudicated offenders, 76.5 percent were convicted of their current gun crime. These convicted offenders were usually sentenced to incarceration (87.2 percent), with sentences ranging from 6 to 120 months (mean, 32 months; median, 18 months; mode, 12 months). The arrested offenders associated with the IBIS matches were more serious offenders than 514 adults arrested for homicide, gun assault, gun robbery, and illegal gun possession in Boston in 1995.7 Of these offenders, 76 percent had been arraigned in Massachusetts courts at least once before their current gun crime arrest; 37 percent of these known offenders had prior felony convictions. The IBIS offenders were also more likely to be convicted of their gun crimes than the 1995 cohort of Boston gun offenders who had a 37 percent conviction rate for past armed violent felonies and gun possession offenses. The Use of IBIS Matches in Gun Enforcement Operations To further document the use of IBIS matches in Boston’s interagency gun violence prevention efforts, available official data associated with 44 IBIS matches made by the BPD ballistics unit in 2003 (incident reports, arrest reports, intelligence reports, ATF trace data) were collected and analyzed. These data were presented to the Boston Police investigators and Suffolk County assistant district attorneys who participated in the interagency working group meetings during 2003. The use of the 44 matches in their gun violence prevention activities was discussed in a series of interviews and focus group sessions. The 44 matches linked 108 incidents (mean of 2.5 incidents per match, range 2–8 incidents). Collectively, 59 victims and 28 arrested individuals were involved in the 108 incidents. The presence of offenders, victims, and witnesses to interview about the gun crime varied across the events: 7 These data were collected as part of an unpublished study of gun offender criminal histories in Boston and other cities and are available on request from Anthony Braga (see also Braga, 2003).
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Ballistic Imaging 75 percent of the matches (33) had victims associated with at least one of the linked incidents; 59.1 percent of the matches (26) had arrested offenders associated with at least one of the linked incidents; 18.2 percent of the matches (8) did not have witnesses for any of the linked crime scenes. Crime scenes that did not have any witnesses were linked to crime scenes that did have witnesses in 47.7 percent of the matches (21). In 34.1 percent of the matches (15), witnesses were available at all linked crime scenes. Guns were recovered in 25 of the 44 matches (58.8 percent): 13 of the 25 guns (52.0 percent) were traced by ATF to the first retail purchaser; 11 (25 percent) matches involved a link to a homicide incident (one linked two homicides). The investigators and prosecutors strongly believe that all IBIS matches added general investigative and intelligence value to their operations. However, not all matches linked information that resulted in significant additional investigative activity. Matches involving homicide incidents were more likely to generate significant investigative leads when separated from the pool of 44 matches. Homicides are more vigorously investigated than shots fired and gun assaults incidents and, generally, have more evidence that can be linked to other events (such as a victim with a known criminal history). IBIS matches did not generate any direct enforcement actions in 61.4 percent of the 44 matches and 27.3 percent of the 11 homicide matches; see Table A-3. Offenders were charged with the current offense only and not charged with a linked prior gun crime in 34.1 percent of the 44 matches. In the two matches linking homicides, the offenders were TABLE A-3 Results of Information Linked by IBIS-Suggested Matches on Investigations by Boston Law Enforcement Agencies, 2003 Direct Enforcement Actions All Matches (N = 44) Homicide Matches (N = 11) No direct enforcement action; IBIS-suggested match only had general investigative and intelligence value 27 3 Arrest based on current offense, no potential for additional charges in linked crimes 15 2 No arrests and no potential for immediate charges based on linked information 12 1 Significant investigative lead generated by IBIS match 17 8 Arrest made or arrest warrant issued as a result of linked information 8 4 Suspects identified; however, charges not filed because linked evidence was not strong enough 8 3 Case resolved as homicide victim had gun used in prior homicide 1 1
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Ballistic Imaging interviewed about a prior linked gun crime, but only charged in the subsequent homicide incident. Of the matches, 27.3 percent did not have arrests for current offenses or any immediate potential for charges based on linked information. In the one homicide match included in this category, the unsolved homicide was linked to a shots fired incident with no arrests, victims, or witnesses to interview. IBIS matches generated significant investigative leads in 38.6 percent of the 44 matches and 72.7 percent of the 11 homicide matches. The linked information resulted in an arrest or an arrest warrant in 18.2 percent of the 44 matches and 36.4 percent of the 11 homicide matches. Unfortunately, linked information across crime scenes can be highly suggestive of the identity of a violent gun offender but not sufficient enough to support formal charges. In 18.2 percent of the 44 matches and 27.3 percent of the homicide incidents, likely suspects were identified and interviewed but not charged because the information chain connecting the events was not strong enough to justify an arrest. In one case, a homicide investigation was resolved but an arrest was not made because the ballistics link was made from a test fire of the gun recovered from a homicide victim who was a suspect in a prior homicide incident. While all matches were regarded as valuable by the interviewed law enforcement agents, the matches that led to an arrest clearly added the most value to gun violence prevention strategies. The 2003 investigation and arrest of a homicide suspect—for anonymity, referred to as A—provides a good example of the usefulness of links between crime scenes made by IBIS matches. The Boston Police were conducting a surveillance of a known crack-cocaine drug market location in the city. The police witnessed an apparent drug transaction and, after interviewing the suspected customer, they attempted to interview A and B, the suspected sellers. A immediately fled and fired at least one shot at the pursuing officers. After a standoff, A surrendered and was arrested on assault, firearm, and drug charges; a Glock semiautomatic pistol was recovered. During booking, Boston Police officers recovered receipts from A documenting the purchase of the Glock pistol by another person from an out-of-state federal firearms licensee. The Glock was test fired, and the resulting cartridge casing was entered into IBIS. After the automated correlation and a microscopic comparison by a firearms examiner, the casing was matched to a cartridge casing recovered at the scene of a homicide in 2002. Witnesses were present at the time of the homicide but were not able to provide a detailed description of the assailant. Further investigation revealed an ongoing personal feud between A and the homicide victim. As a direct result of the IBIS match, A was charged with murder; A was subsequently convicted and is serving a life sentence for murder in the first degree.
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Ballistic Imaging Estimating the Costs and Benefits of IBIS Braga and Pierce (2004) estimated the cost-effectiveness of the IBIS technology in making ballistics matches in two ways: the cost of making a match and the cost of comparing a piece of ballistics evidence to the existing inventory of evidence. In 1995, the IBIS equipment used by the BPD was purchased by ATF at a cost of $540,000. Reflecting general trends in decreasing technology costs, the same equipment cost $295,000 in December 2003. As of December 31, 2003, the BPD ballistics unit had made a total of 404 cold hit matches involving cartridge casings using the IBIS technology. Using 2003 prices, the equipment costs amount to $730.20 per cartridge casing match.8 There are two reasons to believe that this cost estimate will continue to decrease markedly as time progresses: (1) as more evidence is entered into IBIS, the probability of making a hit will increase and the absolute number of hits will continue to increase; (2) as with the costs of other computer-related technologies, the cost of the IBIS technology will also decline over time. As Table A-1 (above) documents, the addition of the IBIS equipment did not result in new hires by the BPD to staff the ballistics unit. Except for some time invested in training staff to properly operate the IBIS equipment, the direct annual cost to the BPD is zero. The ATF costs can be amortized on an annual basis over the course of the lifetime of the equipment. Importantly, IBIS can routinely scan vast inventories of ballistics evidence in a manner that was for most practical purposes impossible prior to the availability of this technology. IBIS technology allows each newly entered piece of ballistics evidence to be compared against existing inventories that can easily reach thousands in a matter of minutes. Before IBIS, making cold hits was an ad hoc process that was limited by the ability of firearms examiners to compare selected cartridge casings to the larger inventory of crime scene casings in the property of the ballistics unit. For example, in September 1993, Detective John Mulligan was shot, execution style, five times in the head with a .25 caliber firearm as he sat in his car while working as a private security detail at a Walgreens pharmacy in the Roslindale neighborhood of Boston (Braga and Pierce, 2004). In an attempt to develop more information on the case, the BPD selected 50 .25 cartridge casings from recent violent crimes in the surrounding neighborhood. Five 8 This represents an update over Braga and Pierce (2004), who reported a cost of $744 per match based on 396 matches made through early December 2003. However, either estimate is far lower than the cost estimates of $12,000 per cartridge case hit suggested by Kopel and Burnett (2003). The difference in estimates is the result of comparing IBIS in one jurisdiction (Boston) that has been operating comprehensively for a number of years to an aggregate of 222 systems across the United States, some of which received the technology only a few months before the Kopel and Burnett report and were not yet fully operational.
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Ballistic Imaging firearms examiners spent 10 8-hour days comparing the selected casings to the recovered crime scene evidence (Braga and Pierce, 2004). Unfortunately, this intensive effort did not result in a match.9 Braga and Pierce (2004) used this anecdote as an opportunity to estimate the cost of comparing one cartridge casing to the BPD’s inventory of cartridge casings. In December 2003, the average BPD firearms examiner earned $50,000 per year. As such, the BPD would pay one firearms examiner $2,083.33 to work 10 days. Five firearms examiners would cost $10,416.67 for the same time period. As the story describes, the five examiners compared 50 casings to one piece of evidence during this time period. Therefore, it cost the BPD $208.33 to compare two cartridge casings. Assuming the BPD had unlimited resources and firearms examiners, it would cost more than $2.6 million to compare one cartridge casing to every one of the more than 12,700 cartridge casings in the BPD’s inventory as of December 2003. Braga and Pierce (2004) observe that these figures were not meant to be precise estimates; rather, they simply illustrate that the cost of human examiners routinely scanning existing ballistics evidence inventories for likely matches is prohibitive, and even this assumes that human resources are available to make such comparisons. In contrast, the cost of routinely scanning existing ballistics evidence inventories to find potential matches, using IBIS equipment is modest. It is important to note, however, that these cost-effectiveness estimates were calculated on basis of the performance of IBIS in matching cartridge casings. IBIS technology is not as cost-effective in making ballistics matches with recovered bullet evidence. Between 1995 and 2003, the Boston Police only made eight cold hit bullet matches. Using 2003 prices, the equipment costs amounts to $36,875 per bullet match.10 The benefits of IBIS to gun enforcement operations can also be assessed by estimating the number of arrests resulting from IBIS matches to the number of arrests that would have been made from traditional methods of making cold hits if the IBIS technology had not been available. In 2003, 18.2 percent of IBIS matches resulted in an arrest or the issuance of an arrest warrant for a linked gun crime. Since IBIS was adopted in 1995, 412 matches were made by the end of 2003. Using 2003 figures as a reasonable basis to estimate the role of IBIS in making arrests, 75 (18.2 percent of 412) matches would have generated an arrest. If IBIS had not been available, traditional ballistics methods would have yielded about 81 total matches between 1995 and 2003 (8.8 per year multiplied by 9 years) and about 9 The two suspected killers were arrested after the .25 handgun was found in a vacant lot some 100 yards from the home of one of the suspects in the Dorchester section of Boston. 10 This figure is still much lower than the $195,000 per bullet hit estimate suggested by Kopel and Burnett (2003).
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Ballistic Imaging 15 would have yielded arrests for linked gun crimes (18.2 percent of 81). Therefore, IBIS can be associated with making arrests in an additional 60 linked gun crimes—4.4 times as many arrests for linked gun crimes—when compared with the performance of traditional ballistics methods. CONCLUSION The capabilities and cost advantages provided by IBIS technology can significantly increase the use of ballistics evidence by law enforcement. Ballistics matches made by IBIS are an important part of Boston’s interagency efforts to prevent gun violence. According to Boston law enforcement agencies, all matches have strategic value in understanding ongoing violent conflicts among gangs and criminally active groups that are major parts of the city’s violence problem. The IBIS matches, and the information chains that result from the linked gun crimes, are used to mount investigations of suspected violent gun criminals and to develop and implement violence reduction strategies to prevent additional gun crimes from happening. The BPD further asserts that the ability of IBIS to make quick comparisons to a large inventory of ballistics evidence has yielded a number of high-profile investigations that would not otherwise have been possible. For example, in 2000, a 9mm handgun was matched to 15 other gun crimes in Boston, Brockton (MA), Randolph (MA), and Providence (RI) (NIBIN Program, 2001). Boston IBIS matches, coupled with an interagency focus on apprehending and prosecuting violent criminals by all available law enforcement means, were also associated with the arrest of very serious gun offenders and high conviction rates for their immediate gun offenses. The results of this research study suggest that the IBIS technology significantly increased the productivity of the BPD ballistics unit in linking guns crimes. The analysis found that the adoption of the IBIS technology was associated with a more than six-fold increase in the number of cold hit matches per month. Clearly, the IBIS technology significantly increases the ability of law enforcement agencies to make ballistics matches across crime scenes. The cost-effectiveness estimates and qualitative evidence also suggests that the IBIS technology allows law enforcement agencies to make hits that would have otherwise not been possible. Before IBIS was adopted by the BPD, ballistics matching across gun crime scenes was an ad hoc and tedious process. Now, the BPD can systematically compare recovered gun crime evidence to its entire inventory of evidence with little effort. The unfortunate 1993 Boston police officer execution-style slaying and the well-known 2000 investigation involving one firearm used in 15 separate incidents provide stark contrasts in the ability of the BPD to link the use of firearms across gun crime scenes. The experience of the BPD indicates that the use of IBIS technology
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Ballistic Imaging should be accompanied by a department-wide commitment to comprehensively image all ballistics evidence collected by a law enforcement agency. Without such a commitment, one of the major advantages of IBIS, the ability to routinely scan large inventories of evidence for potential links, is obviously reduced. Using the Boston experience as a model, the U.S. Attorney’s Office in the District of Massachusetts has collaborated with the Massachusetts State Police to set up a process for collecting and analyzing ballistics evidence to aid gun law enforcement operations in 11 target cities for the U.S. Department of Justice Project Safe Neighborhood initiative. The Massachusetts U.S. Attorney’s Office provides the state police with $35,000 per year to support the overtime that is necessary to ensure timely ballistic imaging at the state crime laboratory. The steps of this process are as follows: Local evidence collection: Participating police agencies must collect all evidence at gun crime scenes, which includes the collection of crime gun evidence at shots fired scenes where no injuries or fatalities are reported. Transfer to evidence officer: Once the crime scene ballistics evidence is collected, it must be immediately transferred to the department’s evidence officer. Transfer to Massachusetts State Police: The evidence officer must immediately submit the ballistics evidence to the state police crime laboratory. Timely ballistics examination: The state police must immediately image the crime scene evidence and determine whether a match exists within its inventory of ballistic image evidence. Report to investigators: The results of ballistics examination are to be communicated by state police firearms examiners to investigators from the submitting agency as soon as available. Report to gang unit: The results of the ballistics examination are to be shared with relevant units within the police department, such as the gang unit, to see if additional information can be developed on the locations, individuals, and crime gun involved in the match. Report to prosecutors: The information must be shared with federal and local prosecutors to coordinate priority prosecutions. Regional or statewide analysis: Because violent criminals sometimes cross jurisdictional boundaries, ballistics evidence is to be analyzed at larger levels of aggregation beyond the city where the immediate offense occurred. In contrast to state-level systems that image guns not involved in crime (for a critique, see Kopel and Burnett, 2003), ballistic imaging systems that are built on comprehensive imaging of all recovered gun crime evidence and
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Ballistic Imaging supplemented by strategic data analyses and intelligence gathering seem to show great promise in apprehending violent gun criminals. The Boston experience with ballistic imaging technology suggest that ATF’s NIBIN program, with appropriate support, can ensure that participating jurisdictions are well trained in the practices of comprehensive ballistic imaging.