Gary L. Williams & Jeffrey Fisher
The law enforcement community has long relied on fingerprints to identify criminal offenders. Today, there is another alternative available to help law enforcement to identify criminal offenders. The FBI now offers law enforcement agencies the benefits of its National Palm Print System (NPPS) to employ palm prints as another useful tool for latent examiners to make an identification.
A palm print can potentially be more helpful for identification than a fingerprint, because it is a much larger area of body surface with more characteristics for comparison. A palm print can have approximately 1,500 characteristics—approximately 10 times as many as a fingerprint. It should also be noted that a subject might be more reluctant to deliberately mutilate the palms of their hands as they are more central and essential to the function of a hand than fingertips.
Palm prints can be useful for identifying subjects if fingerprints are unavailable or not usable. And just like with fingerprints, jails and law enforcement agencies must capture them correctly to benefit from the palm print comparisons the FBI can provide.
What Is NPPS? NPPS is the FBI’s repository of palm prints. When the FBI launched NPPS in 2013, this greatly expanded law enforcement’s access to palm prints, which had previously been stored by individual agencies in their own databases. NPPS, which exists as part of the FBI’s Next Generation Identification (NGI) System, contains palm print images submitted by law enforcement agencies across the nation. NPPS provides agencies with search capabilities to a repository of civil and criminal biometrics.
Currently, 49 states along with agencies in Washington D.C., Puerto Rico, and Guam submit palm prints to NPPS. And as of this writing, the repository contains 51.6 million palm print images associated with 25 million records—all of which are available for investigative leads. It has been shown by reports that many law enforcement agencies have made successful arrests from palm print matches in the system.
The Importance of Good Palm Images The booking process can be difficult, especially when subjects refuse to cooperate. However, some extra effort during the print-capture process is worthwhile because more than 18,000 law enforcement agencies rely on the quality and completeness of palm print information submitted to NPPS.
The success or failure of palm print quality begins at the booking station. To give palm prints the greatest chance of success, booking officers need to invest attention to detail and understand palm print features.
Some submitting agencies have low rates of success with enrollments of palm prints because the NGI System or examiners cannot distinguish important details in the prints. This happens when the images are captured incorrectly during a subject’s booking and incomplete or incorrect pattern areas are recorded. Scott A. Rago, chief of the FBI’s Biometric Services Section, has stated if agencies submit incomplete or low-quality palm images, “the images are rejected for submission into NPPS and do not benefit future searches.”
Figure 1. Hand Anatomy
Figure 2. Full palm print with writer's edge
Figure 3. Upper and lower palm images
A complete palm print is not only the flat, middle part of the hand—it is a handprint that includes the whole hand from the fingers to the wrist. The FBI estimates more than 90% of palm print rejections occur because agencies do not capture the top joints of the fingers, referred to as the distal parts of the palm print. Most agencies that experience rejections of their palm print submissions could reduce their rejection rates tremendously by making sure to capture these. Figure 1 shows hand anatomy including the distal parts.
Another problem for palm print submissions is low-image quality. This can include images that are excessively smudged, too light, extremely dark, dirty, blurry, or low in resolution. Substandard quality prints in NPPS cannot be searched against the Unsolved Latent File, which is the FBI’s repository of unidentified latent prints from unsolved cases resulting in the inability to identify suspects.
It is not known exactly how many criminal investigations are negatively affected by these palm enrollment failures with agencies submitting approximately 25,000 palm print searches per month on average, but it is logical to conclude that more matches would result if they captured better quality images.
The full palm print area is from the top of the wrist bracelet to the tips of the fingers. Two accepted ways to properly capture full palm prints are four-scanned images and six-scanned images. As shown in Figure 2, both methods capture images that include fingerprints and the full palm, resulting in a complete set of palm prints for a subject.
A complete six-image palm print includes the upper and lower images from both hands with the left and right writer’s palms, making a total of six images. This is shown in Figure 3. The lower palm image should show from the wrist bracelet to the top of the first finger joint (interdigital area or proximal finger joint) and should include the thenar and hypothenar and areas of the palms. The upper image should show from the interdigital area to the upper tips of the fingers.
By providing a combination of the upper and lower images that overlap in the middle of the images, a booking officer can establish one complete palm print record belonging to the same person. The NGI System or examiners can verify this overlap by matching the ridge details and structures in the interdigital areas in common for both images. If the upper palm print image includes fingerprints, the NGI System or biometric images examiners can match the palm print to a tenprint record (i.e., fingerprint images of all 10 fingers) to confirm the identity of a subject.
ncorrect printing—especially lack of distal images—causes rejection of submissions. To perform an automated validation of the palm prints, the NGI System needs at least one fingerprint from each hand. If a palm print submission does not contain all the necessary distal images, the submission will fail. Some agencies may not have the necessary equipment to capture palm print images correctly, but the main reason for incorrect or insufficient submissions is the lack of training on how to produce a good quality image.
Success Story from Las Vegas The FBI uses various initiatives to raise awareness of NPPS and increase participation. One of those initiatives is the Biometric Identification Award program. This award program recognizes major violent crime cases that agencies solve by using the NGI System. In one example, the Las Vegas Metropolitan Police Department (LVMPD) won the 2018 award for using NPPS to identify a subject. A video about this case and information about other cases is available on the FBI’s Biometric Identification Awards webpage found at www.fbi.gov.
In 2016, the LVMPD investigated an incident involving an elderly female victim who lived alone. She was asleep when an individual pried open her bathroom window and entered her apartment. The suspect went to her bedroom and attempted to sexually assault her. When she resisted, the subject ended his assault and demanded money. The victim gave the man $26, and he fled through the front door. The woman sustained injuries to her arms, back, and mouth during the attack.
The LVMPD detectives investigated the incident without success. They obtained several latent palm prints from the windowsill in the victim’s bathroom, but their search against the LVMPD database produced no results. Detectives then initiated a search through the NGI System, which returned a match. Detectives learned the identity of the suspect within 24 hours of the crime.
Two days later, the subject was arrested and charged with burglary, robbery, battery to commit sexual assault, and attempted sexual assault. In 2017, the suspect pleaded guilty to a felony charge of attempted sexual assault and was ordered to register as a sex offender. He was sentenced to 8 to 20 years of incarceration and lifetime supervision following his release.
FBI Support To assist agencies and ensure NPPS has good quality palm prints, the FBI works with submitting agencies to correct issues with the capture process. The FBI’s Guidelines for Capturing Palm Prints and Supplementals and Recording Legible Fingerprints are published on the FBI’s website at www.fbi.gov. The FBI will continue to expand and provide useful resources for law enforcement agencies.
As NPPS expands and develops, it will become increasingly more helpful for the criminal justice community. Agencies that would like more information can contact the Palm Services and Analysis Team at 304–625–2849 or send an email to palm_prints@fbi.gov.
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Gary L. Williams has been employed by the FBI’s Criminal Justice Information Services Division for 28 years and has held several positions working on multiple projects during this time. Most notably, he worked on the team that developed the NGI System that is in use today. Mr. Williams is currently the supervisory management and program analyst of the Palm Services and Analysis Team.
Jeffrey Fisher is a writer-editor with the FBI. He has a master of science degree from West Virginia University and has worked for the FBI for 24 years as a biometrics expert, manager, and writer. He has authored numerous articles about the FBI’s various crime data collections and systems. He can be reached by email at jfisher2@fbi.gov.