Advances in technology have gradually contributed to fingerprint examiners' efficiency in developing, enhancing, recording, and comparing fingerprints. Using fluorescence to develop latent prints, examiners can find more prints, more easily. As discussed in the previous section, lasers and forensic light sources can both produce inherent fluorescence and stimulate it in fluorescing powders and dyes. Taken together, these techniques represent one of the most significant developments in the field ever.
Similarly, reflected ultraviolet light can be used to enhance latent prints. The National Police Agency of Japan pioneered this method, and a commercially available system is marketed under the acronym RUVIS. Several laboratories, including the NYPD lab, have purchased this equipment and begun to evaluate it.
Magnification is useful as a fingerprint enhancement, and technology has made extremely high magnification possible. Typically, however, excessive magnification creates more problems than it solves when it comes to viewing fingerprints. Since the scanning electron microscope is capable of incredibly high magnification, on the order of 400,000X or more, it would not appear to be a likely candidate for use in visualizing or enhancing latent prints. However, by using low magnifications of latent prints developed using small particle reagents, some very good results have been obtained.
Electronic fingerprint enhancement is one area that modern digital imaging and high-speed computers have facilitated. Economical and readily available software such as Adobe Photoshop allow the electronic enhancement of vague fingerprints or the removal of interfering background patterns. Many times simply adjusting brightness and contrast of scanned images of fingerprints can provide adequate enhancement to be able to identify the source of a fingerprint.
A type of technology that eliminates a step in the fingerprint recording process is the Livescan fingerprint. This is a fingerprint obtained electronically without the intermediate step of getting an impression on paper. A number of different technologies have been adapted to accomplish this, all of which rely on the sensing of differences in the ridges and valleys that make up the friction ridge detail. These technologies include thermal sensing, ultrasonic reflection, optical reflection, and differential capacitance. The most popular Livescan technology relies on optical reflectance. The equipment is quite simple to use, requiring only that the finger be placed on a glass scanner that is part of the case housing the hardware; however, this technology is still in its early stages and has yet to replace inked fingerprints.
There is a tedium associated with the visual comparison of fingerprints that surpasses other areas of physical evidence due to the quantity of prints each examiner must deal with on a daily basis. Ever since law-enforcement agencies began using fingerprints to identify criminals, there has been a need to streamline this tedious task. Despite many ingenious methods that have been developed to increase the efficiency of the manual indexing and searching of fingerprints, visual comparison has remained very time consuming.
The development of digital imaging and the high-speed computer set the stage for law-enforcement agencies to explore ways to automate some or all of the comparison details involved with fingerprint evidence. The comparison of fingerprints involves two steps: First the fingerprint of interest must be compared against literally millions of others, and second, if a candidate is found, verification is required. Clearly, using a computer would have the greatest impact on workload in the first step, where multiple comparisons are required. An automated fingerprint identification system, AFIS, which compares electronically generated fingerprint data, was the result of this need.
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