Why Law Enforcement Agencies Should Capture Complete Palm Prints
November 19, 2024
The FBI’s National Palm Print System (NPPS) enables the storage of known palm prints and the search of latent palm prints left at crime scenes. Currently, the NPPS repository in the FBI’s Next Generation Identification (NGI) System maintains more than 65 million palm-print images tied to more than 29 million unique identities. All those identities are associated with a tenprint record. They are available to law enforcement agencies for potential investigative leads.
Palm prints are a trusted, valuable tool that law enforcement can use to help identify suspects. NPPS staff estimate that 30% of latent prints found at crime scenes come from the palm. The palm, which is a larger hand area than fingertips, has more characteristics for latent examiners to compare and match than fingerprints. A palm print can have about 1,500 definable characteristics for identification, while fingerprints usually have about 150. Nearly all states, some territories, and the District of Columbia submit palm print images to the NPPS. The value of palm prints is evident from the numerous success stories reported by participating agencies.
The NPPS unfortunately cannot enroll and process all the palm prints that law enforcement agencies submit, due to lack of complete palm images. A significant number of states have enrollment success rates under 80% due to low-quality or incomplete images, and some have success rates under 50%.
Palm prints that fail enrollment in the NPPS can never be searched against latent records in the Unsolved Latent File. This can result in a failure to identify potential suspects, which may contribute to crimes remaining unsolved. So, what can be done to reduce enrollment failure?
The main factor to improve palm-print enrollment rates
The most common reason for palm print enrollment failure is incomplete image capture. A complete, usable set of palm-print images includes the whole inner surface of the hand, including the insides of the fingers out to the last joint along with the center of the hand down to the wrist bracelet—which people commonly call the "palm." The last joint, which is called the "distal area," features the fingerprints. Capturing the fingerprints, along with the rest of the palm, results in a complete set of print images that maximizes the chances of successful identification.
A complete palm print includes the wrist bracelet and the distal areas and all parts between.
The distal images are important for ensuring the correctness of the palm print and enrollment. This is because criminal history records in the NGI System are based on fingerprint identification, and the distal part of the fingers contains the fingerprints. If a palm-print submission correctly includes the distal images, the system can check the fingerprints against the palm areas, ensuring they are part of the same hand. Without the distal images, the system cannot perform this check.
The NGI System uses the sections of a complete palm print submission to link the parts of the palm and the fingerprints together in a verified record.
The equipment that many law enforcement agencies have may be unable to capture the entire palm print in a single image due to a small scanning surface that only prints portions of the submission at a time. The FBI urges those agencies to capture each portion of the palm print submission completely so the system can create a complete record from those portions. Agencies can consult and download the FBI’s “Palm Print Capture” poster (see example below) for guidance on how to record a complete set of palm prints using multiple scans.
The “Palm Print Capture” poster shows how to record a 4- or 6-image palm print submission.
To support partner law enforcement agencies and ensure the NPPS has a gallery of high-quality palm prints, the FBI is proactively working with state submitting agencies to address any palm print enrollment issues the state may have. A palm print capture guide and references are available at fbibiospecs.fbi.gov and le.fbi.gov/science-and-lab/biometrics-and-fingerprints/biometrics/biometric-training. We encourage law enforcement agencies to contact the Palm Services and Analytical Team at 304-625-2849 or via email at palm_prints@leo.gov. FBI palm-print subject matter experts are ready to help.
