This project explored the use of Non-Identifiable Fingermarks (NIFMs) on loaded ammunition to link suspects with firearms. It is a continuation of a series of NIJ-sponsored research efforts to evaluate and develop the potential of NIFMs both as an investigative tool and as admissible evidence.
NIFMs are fragmentary, partial fingerprints that are insufficient for identification. Current forensic science practices set these fingermarks aside, leaving them unexamined. Prior research has established that NIFMs occur frequently and have strong associative value. Accordingly, they represent an untapped source of evidence with a strong potential contribution.
As the next step in these efforts this project produced a realistic test of the actual contribution of NIFMs, when applied to a specific important evidentiary problem: linking suspects with firearms. The goals being to first address the specific need, and more importantly to lay the groundwork for further applications of this unused form of evidence to address a broad range of forensic needs in the justice system.
The contribution of NIFMs when applied to this important evidentiary problem provided answers of how often NIFMs occur on naturally loaded handgun ammunition and what range of associative values can be expected. By comparing these results to those obtained from using only identifiable fingerprints, the potential added impact of NIFMs is illuminated.
Under realistic conditions unfired ammunition was collected from handguns after they had been loaded by their owners, each using newly purchased ammunition and their accustomed loading practices. The ammunition cartridges were processed for fingerprints using commonly employed forensic laboratory methods and all fingermarks showing four or more ridge characteristics were considered. Expert examination of these marks determined which were identifiable (conventionally used fingerprints) and which were NIFMs. Associative values of the marks (estimating how often a match might occur at random) were determined using a well-defined, calibrated method.
1263 rounds of ammunition were collected from 164 handguns. Fingermarks judged identifiable (64) were found on 4.7% of rounds representing 21.3% of handgun loads. When NIFMs were considered (another 414 fingermarks), the number of rounds rose to 27.2%, representing 65.9% of handgun loads. According to international reporting guidelines, 80% of the NIFMs provided strong support for association (as in a random match occurring less than once in a thousand times). Although differences in the numbers of NIFMs found were seen among different ammunition calibers and handgun types, each group showed NIFMs with strong association on at least 1 in 5 ammunition cartridges.
The project findings clearly demonstrate the common occurrence of NIFMs of high associative value on loaded handgun ammunition. For this application it has been shown that under realistic operational conditions a six-fold increase in useful associative evidence results when NIFMs are included along with conventional fingerprints. This finding is reasonably generalized to expect a similar increase in useful evidence when NIFMs are used for other items collected as evidence, or as part of the general fingerprint processing of crime scenes.
This is an extraordinary contribution to the specific problem of associating handguns to suspects, and notably one that does not require any additional investment in crime laboratory equipment nor any additional personnel skills. This application of NIFMs warrants immediate attention, with application to criminal investigations, the development and testing of alternative implementation protocols, validation of these protocols, and development of robust quality assurance procedures.
Additionally, this illustrates the even greater potential that might be achieved through further applications of NIFMs to provide more rapid or cost-effective alternatives in routine operations or break-through opportunities in unsolved crimes and cold cases.
(Author abstract provided.)