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PART Iv Future Directions

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10 Microstamping:   Alternative Technology for   Tracing to Point of Sale Contemporary firearms identification and ballistic imaging techniques  are  predicated  on  the  deposition  of  markings  on  evidence  as  a  result  of  r   andom  variation  in  key  processes—the  manufacturing  of  firearms  and  ammunition parts and the mechanical operations and controlled explosions  involved in the firing of a gun. The main objective of a national reference  ballistic image database (RBID) is to use an image catalog of these mark- ings  to  provide  an  investigative  linkage  between  evidence  collected  at  a  crime scene and the original point of sale of the weapon. However, it may  be useful to consider a completely alternative approach to arriving at the  same goal: altering firearms so that, on every firing, they impart a known,  unique, and unalterable marking on spent casings, rather than relying on  the toolmarks generated by the firing process. If  such  known  markings—for  instance,  a  gun-specific  alphanumeric  code—are  logged  at  the  point  of  sale,  the  same  goal  as  a  national  image  database would be achieved: a spent casing recovered at a later crime scene  could  be  rapidly  traced  back  to  the  point  of  sale  by  reading  the  etched  marking. Likewise, known and individual markers could be placed directly  on  individual  pieces  of  ammunition;  again,  if  the  component  codes  in  a  box of ammunition are logged at the point of sale, investigative leads could  result later in time when pieces of stamped ammunition are found at crime  scenes. The question is whether these alternatives compare favorably to a  national RBID, in terms of cost, accuracy, or time savings. This  kind  of  technology—known  as  microstamping—has  become  a  prominent  part  of  the  contemporary  debate  on  “ballistic  fingerprinting”  

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 BALLISTIC IMAGING and enhancing forensic identification technology. In October 2007 legisla- tion requiring microstamping on internal parts of new semiautomatic pistols  was signed into law in California, to take effect in 2010. It is also telling  that  long-proposed  (but  never  enacted)  federal  legislation  calling  for  the  creation of a national RBID was revised in the 109th Congress to require  microstamping instead. Because microstamping has become so enmeshed in  the policy debate, we describe the technology and consider its development.  However, because it is not a direct task of this study, we refrain from offer- ing formal recommendations or findings specific to microstamping. This chapter begins by describing the concept of tagging as a form of  identification  from  a  historical  and  technical  perspective  (Section  10–A)  before describing current proposals for microstamping related to ballistics  evidence  (10–B),  including  the  California  law.  Sections  10–C  and  10–D  focus on specific technologies for microstamping firearms parts and ammu- nition, respectively; brief general commentary is offered in Section 10–E. 10–A TAggINg AS A MEANS OF IDENTIFICATION Identification tagging or “labeling” crafted or manufactured items has  its  origins  in  antiquity  when  the  first  artist  signed  his  or  her  work  or  a  person wished to uniquely identify an object to reflect its point of origin,  manufacture, or ownership. Unique “signatures,” either literal or represen- tative symbols, have continued to be used for these purposes to the present  day. Such markings of authorship or origin remain one of the evidentiary  links used to identify art objects, for example, or to link “lost” masterpieces  to their creators over the years.  Over time, manufacturers transitioned from simple graphic insignia to  digital serial numbers to uniquely track their goods for a variety of reasons:  the  increasing  scale  of  mass  production,  the  need  for  accurate  sequential  tracking  of  goods  during  manufacture,  and  the  necessity  of  monitoring  lot  specificity  and  quality  in  response  to  legal  oversight.  The  manner  by  which  serial  numbers  are  applied  to  objects  is  as  varied  as  the  products  produced. Whether bar-coded, machined, cast, painted, or laser-engraved,  serial  numbers  provide  a  readily  discernable  means  to  uniquely  mark  an  object to provide provenance of an object.  Because  serial  numbers  can  link  manufactured  objects  to  their  own- ers, they provide a valuable tool to law enforcement in developing leads in  criminal cases. Two well-known illustrations of the utility of serial numbers  in investigating criminal cases—the bombings of the World Trade Center  in New York in 1993 and of the Alfred P. Murrah federal office building  in Oklahoma City in 1995—involved the use of vehicle identification num- bers (VINs). A car’s VIN is roughly the automotive equivalent of human 

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 MICROSTAMPING DNA: although it can be altered, it generally sets a vehicle apart from the  millions  of  other  vehicles  in  circulation.  U.S.  automobile  manufacturers  began  stamping  and  casting  identifying  numbers  on  cars  and  their  parts  in the mid-1950s. Originally developed to give an accurate description of  the vehicle as mass production increased, the use of VINs grew in the early  1980s when the National Highway Traffic Safety Administration (NHTSA)  required  that  all  road  vehicles  must  contain  a  17-character  VIN  (Insur- ance Information Institute, 2006). The required VIN number identifies the  country  of  manufacture,  the  manufacturer,  the  vehicle  type,  and  specific  descriptors of the individual vehicle (49 U.S.C. 565); as a unique DNA-style  number for each individual vehicle, it can be used to track recalls, registra- tions, warranty claims, thefts, and insurance coverage.  Investigators sifting through the rubble in the parking garage under the  World Trade Center following the 1993 bomb explosion found fragments  bearing a VIN corresponding to the number of a missing van. Tracing the  van  to  a  Ryder  truck  rental  agency  led  to  the  arrest  of  a  suspect  in  the  bombing; leading in turn to the capture of additional suspects (Parachini,  2000).  In  the  1995  Oklahoma  City  case,  a  VIN—along  with  a  partial  license plate—were recovered at the scene of the explosion; this led to the  determination that the explosive was contained in a 1993 Ford rented by  Ryder  in  Junction  City,  Oklahoma.  Subsequent  contact  with  the  rental  agent allowed investigators to develop a composite drawing of a suspect;  combined with other evidence, this was instrumental in the arrest and con- viction of Timothy McVeigh for the bombing (Michel and Herbeck, 2001).  In addition to the utility of unique tagging marks in furthering investiga- tions, these examples are also illustrative in the context of firearms evidence  for another reason: they suggest the remarkable retention of engraved serial  numbers on metallic components subjected to explosive impact.  10–b ID TAggINg IN FIREARMS IDENTIFICATION As  manufactured  goods,  both  firearms  and  ammunition  are  already  subject  to  conventional  serial  numbering.  The  serial  number  imprinted  on the frame of a firearm can be traced to a point of sale if the weapon is  recovered;  methods  for  the  restoration  of  serial  numbers  that  have  been  defaced by filing or other means are an important part of forensic analysis.  Similarly, boxes of ammunition also bear serial numbers, which may be use- ful in quality control and in identifying defective rounds. What is novel in  contemporary discussion of microstamping or “ballistic ID tagging” is the  potential for generating investigative leads early in the investigative process:  the new technology is meant to link expended rounds of ammunition to a  point of sale without requiring the recovery of the gun itself.

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 BALLISTIC IMAGING 10–b.1 Microstamping Proposals in California, 2005–2006 The idea of a large-scale reference ballistic image database became very  prominent when the most populous state, California, considered the feasi- bility of implementing the technology. Likewise, the issue of direct tagging  or  microstamping  of  firearms  and  ammunition  has  grown  in  prominence  due to developments in California. Microstamping had been referenced as  an “intriguing alternative,” possibly an economical one, in the California  Department  of  Justice  report  on  a  state  RBID  (Lockyer,  2003:6).  Micro- stamping  was  also  raised  as  a  question  by  De  Kinder  (2002b:22)  in  his  independent  review  of  the  California  technical  evaluation  of  a  proposed  state RBID. Subsequently, it was recommended as a research topic by De  Kinder et al. (2004:215).  The emerging discussion of microstamping sparked the introduction of  two bills in the California legislature in spring 2005. The first bill, Assembly  Bill  (AB)  352,  would  have  expanded  the  provisions  of  California’s  penal  code  relating  to  handguns  that  are  “unsafe”  and  hence  illegal  for  sale.  S   pecifically, the bill would declare as unsafe: semiautomatic  pistols  that  are  not  designed  or  equipped  with  a  micro- scopic array of characters that identify the make, model, and serial number  of  the  pistol,  etched  or  otherwise  imprinted  onto  the  interior  surface  or  working  parts  of  the  pistol,  and  which  are  transferred by imprinting  on  each cartridge case when the firearm is fired. AB 352 passed the General Assembly in 2005 and moved to the Senate  for  consideration;  it  failed  passage  in  the  Senate  in  September  2005  but  was made open for reconsideration.1 After a hiatus, the bill was amended  in June 2006 to address some points of concern that had arisen in debate— specifically, that the “technology to create the imprint, if reliant on a patent,  [must  be]  available  to  more  than  one  manufacturer”  and  that  the  state  attorney general has the authority to decide whether different methods for  leaving such unique imprints on cartridge cases are “equally or more reli- able  and  effective”  and,  hence,  could  be  used  for  the  same  purpose.  The  bill received high-profile endorsements from the mayor and police chief of  Los  Angeles  (Newton,  2006),  as  well  as  several  county  sheriffs  (Sanchez,  2006), and the Senate passed its amended bill 22–18 in late August 2006.  However, the Assembly and Senate could not agree on a conference version  of the bill before the end of the 2006 legislative session. The  second  bill,  Senate  Bill  357,  would  have  required  all  handgun  ammunition manufactured or imported into California for sale or personal  1The roll call on the vote was 20–19 in favor, but 21 votes are needed for passage in the  40-member Senate.

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9 MICROSTAMPING use  be  “serialized”—uniquely  identified  in  a  manner  that  permits  visual  inspection,  in  a  manner  so  that  the  identifier  is  maintained  “subsequent  to  the  discharge  of  the  ammunition  and  subsequent  to  the  impact  of  the  bullet”—based  on  standards  to  be  prescribed  by  the  California  Depart- ment of Justice. In other words, the mark must be capable of surviving the  firing of the gun and the impact of the bullet with the target. The unique  identifiers on each piece of ammunition were to be coded or affixed to the  box in which the ammunition is packaged. At the point of sale, then, the  identifier  on  a  box  of  ammunition  (and  all  the  individual  identification  codes contained therein) could be linked to information on the purchaser,  such  as  name,  driver’s  licensee  or  other  identification  number,  and  date  of birth. The bill required the justice department to establish a registry of  ammunition vendors and manufacturers and permitted the assessment and  collection of fees associated with the registration program. In addition to  transmitting the sales information to the state department of justice, the bill  required ammunition vendors to maintain records of sales on the premises  for 7 years. The bill carved out some exemptions to the use and movement  of  serialized  ammunition,  including  crime  laboratories  and  the  transfer  of  properties  from  the  estate  of  a  deceased  person.  Attempts  to  remove  or  obliterate  identifiers  on  ammunition  was  made  a  criminal  offense.  To  support the operational and administrative costs of maintaining the sales  registry, the bill suggested a registration fee of $50 for handgun ammuni- tion vendors and a user fee (not to exceed $0.005 per bullet or round of  ammunition).  Senate  Bill  357  was  passed  by  the  Senate  in  June  2005  and  sent  to  the General Assembly’s public safety committee. However, that committee  referred  the  measure  to  the  appropriations  committee  due  to  uncertainty  regarding the costs of implementing the technology. No further action was  taken on the bill during the legislative session.2  Though the California legislature did not adopt microstamping during  its 2005–2006 session, it did stimulate interest in the idea elsewhere in the  country; see, e.g., Tsai (2006:1) on interest expressed by New Jersey law  enforcement officials in microstamping of firing pins. 2Though the microstamping proposal was not enacted, Senate Bill 357 was in fact passed  into  law;  in  August  2006,  the  bill  was  amended  to  strike  the  entire  text  relating  to  micro- stamped  ammunition  and  was  replaced  with  language  on  collective  bargaining  with  state  employees.

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0 BALLISTIC IMAGING 10–b.2 The California Crime gun Identification Act of 2007 Though the ammunition microstamping bill was not revived in 2007,  the  firearms  microstamping  bill  was  reintroduced  as  AB  1471.3  Micro- stamping remained a high-profile issue through endorsements of the tech- nology by local officials—at least 60 municipal police chiefs and the mayors  of Los Angeles, San Diego, and San Francisco were indicated as supporters  of the bill in the legislative analysis that preceded the state Senate’s vote,  with 14 county sheriffs listed in opposition—as well as other reports.4  AB  1471  set  January  1,  2010,  as  the  effective  date  of  requirements  that semiautomatic pistols bear microstamped identifiers. As it developed  through the legislature, the bill was amended several times. One change was  cosmetic in nature, labeling the bill the “Crime Gun Identification Act of  2007,” but other amendments were substantive: •  The “microscopic array of characters” identifying the make, model,  and  serial  number  of  the  semiautomatic  pistol  were  now  required  to  be  etched “in two or more places on the interior surface or internal working  parts” of the gun, for transference to the cartridge case upon firing. •  The state Department of Justice is required to certify that the micro- stamping technology put into use “is available to more than one manufac- turer unencumbered by any patent restrictions,” or to substitute methods  “of  equal  or  greater  reliability  and  effectiveness”  that  are  unencumbered  by patent restrictions. •  Specific  clarification  was  added  that  the  microstamped  identifier  envisioned by the new legislation is not the same as existing identifier marks  (e.g., manufacturer’s number or serial number) required by law. 3  he  main  content  of  the  new  bill  and  its  2005–2006  predecessor  remained  the  same.  T However, the new AB 1471 omitted some portions of the previous legislation that explicitly  required  a  certification  program  to  ensure  that  some  existing  handguns  meet  or  exceed  the  new standards, including the microstamping provision. 4  n May 3, 2007, the University of California, Davis, issued a press release profiling a new  O study  from  the  California  Policy  Research  Center  (a  center  affiliated  with  the  University  of  California system). The report described the performance of microstamped firing pins when fit  into California Highway Patrol-issue Smith & Wesson .40 caliber pistols and fired up to 2,500  times. The study concluded that the principal markings on the stamped firing pins remained  legible  on  repeated  firings  but  that  finer  markings  (e.g.,  striations  left  by  a  barcode  etched  on the side of the firing pin) were subject to wear; microstamping was said to hold promise  but  required  further  research.  However,  the  report  had  not  undergone  review  at  that  time,  and the press release implied that the study was commissioned by the legislature and linked  to AB 1471; UC Davis chancellor Larry Vanderhoef circulated a letter on May 15, 2007, to  AB 1471 sponsor Mike Feuer and other legislators, apologizing for the premature release of  the report and errors in the press release.

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 MICROSTAMPING Having passed the General Assembly, AB 1471 was approved by the  Senate on September 10, 2007 (see, e.g., Sweeney, 2007), and signed into  law by California Governor Arnold Schwarzenegger on October 13, 2007.  The governor’s signing measure on the bill reads:5 While  I  appreciate  and  understand  that  this  technology  is  not  without  limitations, I am signing this bill to provide law enforcement with an addi- tional  tool  for  solving  crimes  committed  with  semi-automatic  handguns  in California.   Public safety is one of the most important roles of government and I  e   ncourage all stakeholders to work on improving this technology so that  it may become an even more effective crime fighting tool. 10–b.3 Proposed Federal Legislation At  the  federal  level,  the  proposed  Technological  Resource  to  Assist  Criminal  Enforcement  (TRACE)  Act  has  been  offered  in  the  past  sev- eral U.S. Congresses, but has not advanced beyond subcommittee referral.  In  the  109th  Congress,  the  act  was  substantially  revised  to  implement  microstamping  rather  than  a  national  RBID.  Specifically,  the  proposed  legislation  would  forbid  the  manufacture  or  import  of  any  “firearm  that  is not microstamped or a microstamped firearm that does not transfer the  array of characters constituting the microstamp onto the cartridge case of  any ammunition fired from the firearm.” The bill, H.R. 5073, specifically  defines a microstamp as “an array of characters which identify the make,  model, and serial number of the firearm” that is “etched into the interior  surface  or  internal  working  parts  of  the  firearm.”  Although  it  no  longer  called for creation of an image database, the new legislative text retained  language from previous versions that requires “ballistics testing of any fire- arm in the custody of the Federal Government” and establishment of “an  electronic database containing records of the results of the testing” that can  be accessed by state and local law enforcement agencies. The bill was not  enacted in the 109th Congress, and the same legislative text was introduced  in the House of Representatives in the 110th Congress in April 2007. 10–C MICROSTAMPINg OF FIREARMS PARTS The  basic  concept  of  microstamping  firearms  parts  is  to  etch  identi- fier codes into the hard metal components of guns so that—when they are  fired—the markings are impressed on the relatively softer cartridge case or  5  ee http://gov.ca.gov/pdf/press/2007bills/AB 1471 Signing Message.pdf [accessed February  S 2008].

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 BALLISTIC IMAGING bullet. The early work that has been done in the area has focused on the  etching of alphanumeric symbols on the tip of the firing pin. The identify- ing mark is created when the pin hits the primer surface of the cartridge,  and the “image” of the microstamp marking can be read in the base of the  firing pin impression on the recovered casing.  The  microstamped  markings  are  created  by  ultraviolet  (UV)  photo- ablation  by  means  of  a  high-power  laser.6  As  currently  developed,  UV  radiation from an excimer laser or a frequency-tripled solid state yttrium  aluminum  garnet  (YAG)  laser  is  used  to  remove  material  from  the  firing  pin  tip  according  to  a  predefined  pattern.  The  microstamp  is  created  by  illuminating the surface of the firing pin with the laser beam, either through  a lithographically prepared mask or by a maskless procedure in which the  beam  is  positioned  by  a  system  of  computer-controlled  movable  mirrors.  This latter procedure is significantly cheaper than the former.  The individual symbols in the microstamped marking can range from a  few microns tall to several hundred microns, with the optimum size range  being  50  to  100  microns  per  character.  A  smaller  size  compromises  the  mechanical strength of the individual symbols. Due to the high intensity of  the UV beam, the material is removed from the firing pin in a very short  time, typically about 200 milliseconds. To increase the strength of the char- acters in the microstamp, a thin (1 micron) diamond or titanium carbide  layer can be evaporated onto the stamp.  To maintain the functionality of the firing pin, the material between the  characters making up the code is removed only inside a circular area, so that  the characters are raised against a background, but the character tops are  flush with the original surface of the firing pin. This ensures that the overall  tip shape is maintained. It also makes it much harder to remove the marking  without rendering the firing pin useless. When the firing pin hits the primer,  an imprint of the microstamp is left at the bottom of the impression. This  imprint  consists  of  depressions  corresponding  to  the  stamp  characters  or  symbols.   he tip of the firing pin is not the only part of a firearm that could  T be microstamped so that known markings are recovered on evidence fired  in that weapon; however, the other possibilities remain more speculative and  untested at this time. (We discuss one such idea—the etching of markings in  the barrel of a gun, so that a known “barcode”-type identifier is formed on  the soft bullet as it grips the rifling and exits the barrel—in Section 10–C.1,  below.) Alternately, known markings could be imparted on cartridge casings  by placing one or more microstamped patches on the breech block of the  firearm,  surrounding  the  firing  pin  hole;  the  mark  would  then  be  created  as the soft primer surface is forced outward by the ignition of powder and  6  he process is similar to the photokeratectomy process (commonly known as LASIK) used  T in eye surgery to adjust the shape of the cornea.

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 MICROSTAMPING expansion of gases. It may also be possible to place a microstamp identifier  on the firearm’s ejector mechanism or elsewhere on the inside of the chamber  (in the latter case, leaving a mark on the side of the cartridge brass). It is  also reasonable to assume that, as the technology matures, multiple micro- stamped markings could be put on the same firearm, which would serve as  a countermeasure against the defacing or attempted removal of one of the  marks. However, this conceptual approach raises logistical concerns as well  as technical: Would the individual markings or codes have to be identical at  all places on the gun or could they be allowed to vary? The former raises  potential  problems  in  coordinating  interchangeable  parts  with  the  same  identifiers on the manufacturing line; the latter presents the problem of hav- ing to log all the constituent identifiers at the time of sale. 10–C.1 Research Studies In addition to experiments performed by the microstamping technology’s  developer, the present technology for microstamping the tip of firing pins has  been  tested  by  two  firearms  examiners.  Haag  (2004)  submitted  four  firing  pins to the developer—NanoMark Technologies, then known as NanoVia— for  microstamping:  three  of  them  were  for  a  machine  gun  or  automatic  rifle, intended to test the durability of the microstamp engraving over large  numbers of firings. In these test cases, the microstamp took the form of an  eight-character alphanumeric code; firings using the treated firing pins were  conducted using a mix of military and commercial cartridges that varied in  primer hardness and the presence of a lacquer coat on the primer.  Haag  (2004)  found  that  the  marks  were  generally  durable  and  left  readable codes after 2,500 firings. The microstamp also left readable codes  on misfired cartridges, where the pin only struck the primer lightly and the  bullet was not discharged. In some instances, the presence of a red lacquer  coat  over  the  primer  surface—which  might  be  hypothesized  to  absorb  impact  and  degrade  the  markings  left  on  the  primer—actually  served  to  accentuate the alphanumeric code.  The fourth firing pin submitted for microstamping was from a Glock  pistol,  and  was  so  chosen  due  to  the  distinctive  scraping  (and  resulting  scrape  mark)  known  to  occur  in  the  firearm;  this  provided  the  opportu- nity  to  test  the  durability  of  the  stamp  given  the  additional  wear  caused  by  scraping.  A  variety  of  ammunition  was  run  through  the  Glock  with  the microstamped pin, including lacquered primers and casings with pro- nounced  nonfiring  manufacturing  marks.  After  more  than  1,400  rounds,  Haag  (2004)  concluded  that  the  firing  pin  scrape  in  the  Glock  did  not  degrade the microstamped identifier and that neither lacquered primers nor  variation in primer finish and hardness affected the microstamp’s ability to  impart a fixed marking.

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 BALLISTIC IMAGING However,  Krivosta  (2006)  offered  cautionary  notes  based  on  work  with  microstamped  barrels  prepared  at  the  request  of  the  Rhode  Island  Crime Laboratory. He observed that “a number of test fires” from a Rem- ington .22 Long Rifle semiautomatic rifle—a rimfire weapon, rather than  centerfire—were  “illegible.”  The  microstamped  marking  did  not  register  well in the hard brass of the cartridge rim, and marks were further obscured  by repeated (and overlapping) strikes of the pin against the cartridge dur- ing the same  firing sequence  (Krivosta, 2006:42). He  also  questioned the  explicit provision in then-proposed state legislation that the microstamped  identifier on firearms include the gun’s make, model, and serial number—a  large number of characters for a small surface area. Specifically, he referred  to firings involving two Colt .45 pistols with different microstamp configu- rations—one with an eight-character alphanumeric code in “large,” block  capital letters and the other showing the name “NanoTag” surrounded by  the digits 0–9 and the full English alphabet in smaller “type.” With the lat- ter microstamped engraving, “the vast majority of this pin’s characters were  never visualized in the firing pin mark of any of the [ten] expended cartridge  cases  generated  and  examined”  (Krivosta,  2006:42).  Krivosta  (2006:43)  subjected a microstamped firing pin to “intentional defacement:” a process  “easily accomplished in approximately one minute’s time” using a sharpen- ing stone and a portable drill. The removal of the microstamped identifier  in this case did not impede the ability of the gun to fire: the mechanics of  the gun are such that “the pin could have easily been shortened by 0.030  inch or more . . . and the weapon would have still functioned.” Although much of the initial work done to date has focused on placing  microstamped  identifiers  on  firing  pins  (thus  marking  cartridge  casings),  parallel  work  has  continued  on  placing  known  identifiers  on  other  parts  of the firearm. In particular, Carr and Fadal (1997) and Fadal and Nuñez  (2003,  2006)  describe  efforts  by  one  manufacturer,  Glock,  to  develop  an  alternative  rifling  technique  to  impart  “readily  identifiable”  marks  on  b   ullets as they pass through the barrel. The introduction of such a technique  is particularly significant since Glock’s use of polygonal rifling has tradition- ally  made  bullets  extremely  difficult  to  match  in  the  past.  The  work  was  initiated through a special order by the Miami Police Department, and so  the efforts are described in the literature as “the Miami barrel”; Glock has  also referred to the modified barrels as the Enhanced Bullet Identification  System, or EBIS.7  7  he “Miami barrel” followed another Glock experimental effort, the “New York barrel”;  T under a special order from the New York City Police Department, Glock produced a set of  barrels for testing using conventional rifling rather than the company’s usual hammer-forged  hexagonal rifling (Carr and Fadal, 1997:233).

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 MICROSTAMPING Fadal and Nuñez (2006:98) cite Glock as stipulating that “their pat- ented tooling method may be manipulated to create 80,000 possible differ- ent combinations per caliber,” using a “finger-like tool” to etch cuts in the  barrel wall. The markings intended to be replicated with every firing by the  Miami barrels include both gross characteristics that may appear the same  across guns (subclass characteristics) and fine individual detail. Up to 3,000  rounds  were  fired  through  the  latest  iterations  of  the  Miami  barrel;  “the  gross and individual characteristics changed slightly between test firings as  may be expected with wear (e.g., test from 500th shot as compared to test  from 2000th shot),” and test bullets were still distinguishable after 3,000  firings (Fadal and Nuñez, 2006:97). 10–C.2 Advantages Conceptually,  the  microstamping  of  firearms  parts  so  that  a  known,  unique, and repeatable identification tag is imparted on each cartridge case  (or bullet) passing through a weapon has several potential advantages for  forensic identification. •  Assuming that the microstamped identifier is clearly impressed on  spent casings, no special equipment is needed to read the identifier code; it  can be viewed using microscopes already present in standard laboratories.  Conceivably,  some  identifiers  could  even  be  read  at  crime  scenes  using  a  hand  magnifying  lens,  saving  considerable  time.  Again  assuming  a  clear  impression,  identification  based  on  a  microstamped  marker  is  also  easier  to explain and interpret, as it does not require the subjective judgment that  is now central to the interpretation of toolmarks left on a spent cartridge  case. •  The  fixtures  used  to  hold  and  manipulate  the  various  firearms  components  during  the  etching  of  the  microstamp  would  be  specialized  equipment,  but  the  machinery  used  to  perform  the  etching  is  not  highly  specialized.  To  the  extent  that  microstamping  is  performed  on  modular  parts of a firearm—for instance, on firing pins that are manufactured and  tooled  independent  of  other  parts  and  then  assembled  on  the  production  line—the process need not be disruptive of the whole firearms production  cycle. Also, each individual imprint can be created in a short time—typically  around 200 milliseconds—so that the additional overhead in the firearms  production process is small.  •  More than one microstamped identifier could be placed on differ- ent areas of the gun’s firing assembly to increase the likelihood that at least  one identifiable mark will be imparted on cartridge case or bullet evidence  and recoverable by investigators. As noted above, though, multiple identi- fiers raise the issue of coordination, ensuring either that the same identifier 

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 BALLISTIC IMAGING is placed on all parts in the same gun or that all the individual identifiers  are cataloged and linked to the same gun. •  Placing recessed characters on the firing pin, and perhaps adding a  microstamped identifier elsewhere, would make it more difficult to deface  or remove the identifiers without rendering the gun inoperable. •  As  observed  by  Haag  (2004),  microstamped  identifiers  on  firing  pins  appear  to  work  in  some  instances  where  difficulty  would  naturally  be expected, such as ammunition with lacquered primers or misfired car- tridges.  In  the  latter  example,  though,  the  markings  may  require  more  advanced equipment and microscopy to read the marking. •  Microstamping of firearms parts is akin to—and can be perceived  as an extension of—the known and accepted practices of placing a serial  number on all guns sold in the United States and logging that serial number  at the time of sale. 10–C.3 Disadvantages There are also important conceptual disadvantages of microstamping  firearms parts, particularly the firing pin. •  Firearms  microstamping  shares  a  critical  liability  of  an  RBID:  B   arring a radical (and likely untenable) legislative requirement prohibiting  use of any firearm without a microstamped identifier, the coverage of fire- arms microstamping would include only new firearms. Hence, the millions  of firearms currently in circulation would not be affected. Thus, a resource  such as the existing NIBIN database would still be necessary to assist exam- iners with finding links to crime guns that come from the existing stock of  guns. •  Like  a  national  RBID—for  which  the  focus  would  likely  be  on  cartridge  casings  rather  than  bullets,  due  to  the  time  necessary  for  non- destructive test firings to obtain bullet specimens—microstamping strategies  that only impart identifiers on cartridge casings would not be effective in  solving crimes involving revolvers. Similarly, such strategies would also be  hindered  in  instances  in  which  suspects  remove  spent  casings  from  crime  scenes. •  Firing  pins  can  be  replaced  with  relative  ease,  so  a  single  micro- stamped identifier could be defeated by swapping in a new pin. Working  around this would require that newly manufactured firearms parts have to  bear an identifier, and that this information would have to be logged at time  of sale and maintained on file. •  Estimates  of  the  per-unit  cost  to  place  a  microstamp  tag  vary  widely.  Proponents  of  microstamping  suggest  that  the  cost  of  marking  a  firing  pin  would  be  between  $0.50  and  $1.00  (Tsai,  2006),  with  some 

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 MICROSTAMPING estimates as low as $0.15. However, opponents claim the cost to be closer  to $150 (Tsai, 2006), perhaps taking into account the initial capitalization  needed to obtain and operate the equipment or to change production flows  so that component parts are stamped.  •  As discussed by Krivosta (2006), microstamped identifiers may be  difficult to use effectively in rimfire weapons and in low-pressure firings. •  A  database  associating  microstamped  identifier  codes  with  pur- chase information would need to be constructed. Populating this database  would require coordination at the federal and state levels to manage input  from individual firearms dealers. Politically—as is the case with a national  RBID—the  question  of  whether  information  on  the  purchaser,  and  not  just the point of sale, should be logged in the database would have to be  addressed.  Although  the  task  of  setting  up  and  maintaining  such  a  data- base would not be exceptionally difficult, it would still be a large database  and would take resources to manage, purge, secure, upgrade, and operate.  However,  it  is  worth  noting  that  this  database  would  avoid  some  costs  associated with a large-scale RBID, such as the manpower requirements to  acquire images and the storage and preservation of physical exhibits. 10–D MICROSTAMPINg OF AMMuNITION As  described  above,  the  microstamping  of  firearms—as  currently  conceived—is  principally  about  imposing  marks  on  expended  cartridge  casings. Hence, as would be true in a cartridge case-only national RBID,  it  would  not  work  in  settings  in  which  casings  are  not  expelled  at  crime  scenes (e.g., revolvers are used) or are removed from the scene. A different  approach to microstamping focuses on bullets. Conceptually, the microen- graving of individual markers on every bullet offers one prominent advan- tage over other identification technologies, which is that—in time—it would  aid in criminal investigations involving guns that are already in circulation.  Ammunition can be a durable commodity but it is, ultimately, exhaustible,  and new (microstamped) ammunition would eventually replace it. 10–D.1 Ammunition Microstamping Process There are multiple points in a single ammunition cartridge that could,  conceivably,  be  engraved  using  microstamping.  However,  as  experienced  in the analysis of bullet striations, the sides of a (relatively soft) bullet can  warp  or  distort  on  impact,  and  fragmentation  of  the  bullet  is  also  pos- sible.  In  what  follows,  we  outline  the  approach  that  was  advocated  by  Ammunition Coding System (ACS), the firm (and prospective vendor) that  was the focus of attention during debate on the California microstamping  legislation.

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 BALLISTIC IMAGING For  maximum  survivability,  the  ACS  proposal  centers  on  the  etching  of microstamped identifiers on the base of the bullet. In initial work, the  identifier  is  a  six-character  alphanumeric  code.  The  code  is  not  engraved  a  single  time  on  the  base  but,  rather,  repeated  several  times,  in  an  array  over the surface of the bullet base. The goal of this repetition is to “allow  law  enforcement  personnel  to  identify  the  bullet  code  in  cases  where  as  little as 20% of the bullet base remains intact after recovery” (http://www. ammocoding.com [February 2008]).  Though placing the marker on the base of the bullet may enhance its  survivability, it does raise a basic logistical and physical problem at the time  of manufacture: the base of a bullet is no longer visible once the bullet is  seated in the cartridge. Hence, the assembly line process for bullets must  be reengineered so that—at a minimum—the code etched on the bullet in  a single cartridge is known when that cartridge is put in a box or that the  same code is etched later in the process on a visible part of the cartridge  (e.g., the side of the bullet or the exterior of the cartridge case). This con- cern is addressed in part by the etching of the identifier, once, on the surface  of the bullet near the tip. In addition, ACS prototyped a process wherein a  camera records the code marking on the bullet base immediately prior to its  being seated in the cartridge; based on the camera reading, the assembled  cartridge is cycled through additional machinery so that the same code on  the bullet is etched on or near the bottom of the cartridge case. (As a late- in-the-stage process, care is obviously required in devising this process and  creating  the  printed  code  since  the  propellant  and  primer  would  already  be  in  place  in  the  cartridge.)  Once  marked,  the  rounds  are  packed  in  a  cardboard box; a scanner would then read the codes on all the individual  rounds in the box and generate a barcode label to be placed on the box.  This  single,  exterior  barcode  would  then  be  scanned  at  the  time  of  retail  purchase. Later, when a microstamped bullet is recovered at a crime scene,  the individual bullet code would be read and matched to an exterior box  code; that box code would in turn provide the lead to the point of sale. ACS-marked ammunition was subjected to two tests by California law  enforcement personnel. In April 2004 the San Bernardino County Sheriff’s  Department test fired 25 rounds of microstamped ammunition, including  both  .45  caliber  and  9mm  ammunition,  firing  into  media  including  ply- wood, rubber, and a steel door. Three of the bullets were unrecoverable; of  the 22 that were recovered, an identifier code could be read on 21.8 The  California Department of Justice conducted further testing on 200 rounds  of  microstamped  ammunition  in  September  2004.  In  addition  to  firings  8  he exception was a 9mm round fired from 25 yards into 1.5 inches of rubber; only two  T small fragments could be recovered, but apparently not enough of the base endured in order  to preserve the code.

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9 MICROSTAMPING into the side of a car door and standard wall material (plywood, insulation,  and  drywall),  rounds  were  fired  into  gelatin  to  replicate  the  consistency  of  human  bodies.  When  the  bullet  was  recoverable—in  181  of  the  200  firings—the code was again readable in all but one instance.9  10–D.2 Advantages There are at least five advantages to microstamping ammunition. •  Fully  implemented,  microstamped  ammunition  can  provide  valu- able investigative leads from evidence recovered at crime scenes to the point  of sale, and perhaps to the original purchaser. •  As  described  at  the  beginning  of  this  section,  a  key  conceptual  advantage  of  ammunition  microstamping  is  that  it  would,  eventually,  be  applicable  to  the  existing  gun  stock.  Though  ammunition  may  be  stock- piled and can be durable with proper storage, it is possible that much of  the existing ammunition stock would turn over in 3–5 years, and that new  (microstamped) ammunition would gradually replace it.  •  Microstamping ammunition overcomes a limitation of a national  RBID based on cartridge case evidence, in that bullets are almost always  “left” at a crime scene. •  The  base  of  a  bullet—the  proposed  area  for  the  microstamped  identifiers to be located—is more likely to avoid warping or deformation  when the bullet hits a target, relative to the striation marks on the side of  the bullet.  •  The process of reading a code on a recovered bullet is a relatively  quick one, and in some cases may be possible at the crime scene itself. The  key time limitation would be in extracting the bullets from wherever they  may be lodged. As with marks from microstamped firearms parts, the iden- tifiers can be read without specialized training or equipment. 10–D.3 Disadvantages There are also significant disadvantages to microstamping ammunition. •  Although  markings  on  the  base  of  a  bullet  have  proved  to  be  durable in testing in some highly demanding situations—firing into wood  or  a  car  door,  for  example—the  durability  and  survivability  of  markings  on the bullet are still major concerns. Bullets would also be likely to suffer  9  The exception occurred in firings of 30 rounds of .38 Special ammunition into a car door  from 10 yards: 22 of the 30 bullets were recoverable, and it was one of these bullets that was  unreadable.

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0 BALLISTIC IMAGING the corrosive effects of blood and other substances (and the potential for  damage in cleaning them). •  The  investigative  lead  generated  by  recovering  a  microstamped  bullet from a crime scene would be between a crime-related bullet and its  purchaser; as is true with a national RBID, this stops short of directly link- ing ballistics evidence to the particular person who fired the shot. Moreover,  in  complex  crime  scenes  where  multiple  firearms  are  discharged,  micro- stamped  bullet  markings  could  not  directly  lead  to  connections  between  specific bullets and the guns that fired them. •  Though  individual  records  would  be  much  simpler  than  in  an  image database, ammunition microstamping would require a new database  of massive scope, providing the mapping from codes on individual rounds  of ammunition to the code on the box of ammunition that contained them.  This new database would rely on collection from ammunition manufactur- ers and would grow by billions of records (one per piece of ammunition)  each year.  •  In  the  discussion  of  ammunition  microstamping  in  California,  a  perceived advantage was that the second critical data-gathering activity— logging  the  ammunition  box  codes  at  the  point  of  sale—would  require  little or no new resources. Because the technical infrastructure to scan both  ammunition-box barcodes and the barcodes on purchasers’ driver’s licenses  is  already  in  place  among  the  state’s  ammunition  vendors.  However,  in  other states, barcode reading and ammunition sales databases may not be  standard, and practices for examining or recording driver’s license or fire- arm owner’s identification card information may also vary. In such states,  a new system would have to be developed to capture codes at the point of  sale. •  As  is  the  case  with  firearms  microstamping,  cost  estimates  vary  widely,  and  the  inability  to  peg  down  a  per-unit  cost  factored  into  the  inability to pass the California legislation. In terms of initial capital costs  to ammunition manufacturers, Ammunition Coding System stipulated that  “reliable estimates for a complete set of engraving/material handling equip- ment range from $300,000 to $500,000 each.” However, “since approxi- mately  10  billion  bullets  are  sold  in  the  United  States  alone  each  year,  equipment costs, once amortized over the number of bullets produced and  sold are not significant” (http://www.ammocoding.com [February 2008]).  While proponents of microstamping argued that the per-bullet cost would  amount  to  1  cent  or  less,  ammunition  manufacturers  countered  that  the  per-unit cost would be measured in dollars (Yamamura, 2005b). A further  sticking point in the California legislation was the provision for a licensing  fee—per round of ammunition—to be paid, in addition to the cost of mak- ing  the  laser  engravings.  Research  on  the  costs  associated  with  retooling  existing manufacturing plants would have to be conducted as a supplement 

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 MICROSTAMPING to implementation estimates being offered by vendors. The per-round costs  were raised as a particular concern for high-volume ammunition purchasers  such as police forces (Yamamura, 2005a) and the military. •  The  proposed  laser  marking  proposed  by  Ammunition  Coding  S   ystem  involves  evaporation  of  lead,  as  well  as  laser  marking  on  live  ammunition and the use of lasers where explosive compounds are present.  Extensive research would be required to resolve environmental and safety  concerns. 10–E COMMENTARy It  is  not  within  the  committee’s  purview  to  offer  formal  recommen- dations  on  microstamping  technologies—to  suggest  microstamping  as  a  more reliable, less expensive, or generally better alternative than imaging  technologies applied to ballistics evidence, or vice versa. However, we find  that  both  the  microstamping  of  firearms  parts  and  ammunition  possess  the  formidable  conceptual  advantage  of  imposing  discernible  and  objec- tive uniqueness on bullet or cartridge case evidence. Thus, microstamping  could provide a stronger basis for identification based on the evidence than  the  status  quo,  positing  that  uniqueness  arises  from  random  microscopic  phenomena and assuming that unique features manifest themselves in dif- ferent imaging media. However, it is also abundantly clear that substantial  further research would be necessary to inform a thorough assessment of the  viability of microstamping either gun parts or bullets. Particularly necessary  would be credible estimates of the real cost of implementation, separating  initial configuration costs from other life-cycle costs, that accurately take  into  account  the  reengineering  of  existing  firearms  and  ammunition  pro- duction lines. The  emergence  of  microstamping  suggests  a  theme  that  we  explore  further  in  the  next  chapter.  In  microstamping—as  in  the  early  days  of  c   omputer-based ballistic imaging—there has arguably been a push to leg- islate on the basis of the claims and competences of one or two vendors.  We  do  not  challenge  the  work  done  by  the  vendors  who  have  suggested  microstamping to date; they have made solid and worthwhile contributions.  Microstamping  may  indeed  be  a  viable  future  for  firearms  identification,  and  we  strongly  encourage  continuing  research  in  this  area.  However,  we  do  conclude  that  state  and  federal  law  enforcement  would  be  better  served by new technologies and systems developed through richer and more  open competitions, by multiple vendors and research teams and with fuller  appreciation for the integration of new systems with existing manufactur- ing practices.