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Who Goes There? Mobile Fingerprint Readers in Los Angeles County

By Lieutenant Leo M. Norton, Records and Identification Bureau, Los Angeles County, California, Sheriff’s Department

Figure 1. A Los Angeles County sheriff’s deputy
demonstrates how mobile fingerprint readers are
used in the field.
Photo by Mark Minishian,
Los Angeles County Sheriff’s Department

ho goes there? is the challenge issued by those trying to identify an approaching friend or foe. What a guardian does with the response or the lack thereof is the next step in the process of determining the level of danger presented by the unknown individual to the guardian and what or whom the guardian protects. Law enforcement professionals are always concerned with who, what, when, where, and why—these are the basic building blocks of an investigation. Because getting the answer to the who question opens the gate to answering some of the other questions, it is the primary focus of investigators.

Law enforcement professionals like to know with whom they are dealing. Past contact with or a history of the person in question provides clues to what, why, and sometimes where. Solid information regarding the identity of the parties involved—whether they are victims, witnesses, suspects, or persons of interest—can save a lot of time in any investigation.

It is no secret that people do not always tell the truth; the reasons for this are as many and varied as the birds in the sky. Law enforcement professionals have lamented for decades that they are issued a badge and gun but not the ability to read minds. It takes time to develop the instinct to tell the honest from the not-so-honest, and even then agencies do not always get it right. Many bad guys have slipped from the grasp of a peace officer because of their charm and silver tongues or because the officer lacked the right piece of information that would have been enough to put the hooks on the crooks. One county in California has embraced fingerprint scanners as a means to secure that missing piece.

Determining the Right Solution

How a law enforcement professional determines who is who in any situation has recently changed, in a dramatic way, in Los Angeles County. Mobile fingerprint scanners have been deployed widely to various law enforcement agencies throughout the county. Devices are now in the hands of peace officers at the local, state, and federal levels, who are using this tool to overcome the problem of deceptive persons failing to identify themselves properly to law enforcement personnel. This amazing tool means no more wasted time playing the name game or running around in circuitous dialogue trying to verify the identification information given by the detained individual. Many success stories have already been shared, and many more are sure to come.

More than a few vendors offer a mobile fingerprint device, and the devices come in all sizes. Some do more than just capture a fingerprint and send it off to the local automated fingerprint identification system (AFIS). The devices work with mobile digital computers (MDCs) installed in law enforcement vehicles; desktop computers; personal digital assistants (PDAs); or cellular telephones with data transmission capability and a color screen using Bluetooth technology or a tether. Some devices are agnostic, which means they work well with any AFIS, while others work well only with the same vendor’s AFIS.

Figure 2. The Los Angeles County fingerprint reader is
comparable in size to a typical PDA.
Photo by Deputy Mark Minishian, Los Angeles County
Sheriff’s Department

Los Angeles County chose a solution that was light (less than 3 ounces), very portable (less than 4½ inches tall by about 1½ inches wide; see figure 2), and very fast (most returns come back in two minutes or less). The total number of devices deployed in the county will soon reach 2,000. Over 32,000 searches were transmitted in the 2008 calendar year, with over 12,000 positive identifications returned. The county intends to purchase and distribute another 2,000 devices before the end of this calendar year.

Mobile fingerprint devices are carried and used by homicide detectives, coroner staff, and patrol officers on motorcycles and in other vehicles, as well as those on foot or riding public transit buses or trains. The well-developed commercial cell phone system in the Los Angeles area has worked well to support PDAs in this endeavor. Los Angeles County scanners have received positive local media attention and scrutiny from the American Civil Liberties Union. Officers must have good reason to make contact with individuals to identify them using these devices.

Use of fingerprint readers, like any in the law enforcement profession, could be restricted if they are misused. These devices are not intended to be used with every contact or for “fishing” in a crowd; instead, they are designed to provide law enforcement professionals with the ability to gain a positive identification on a person who either has no government-issued identification or possesses one that officers believe is fraudulent or altered. The positive return provided in Los Angeles County includes a photograph, a name, and the latest arrest information.


Currently, the mobile fingerprint scanners in Los Angeles County search only the AFIS managed by the Los Angeles County Sheriff’s Department (LASD); however, the county is currently working on launching an automatic search of the County Wide Warrant System if an identification is made. For now, officers must reenter the identification information into the warrant system to get a return. In the future, the county hopes to be able to reach the California State Department of Justice AFIS if searches fail to find a match in the county database for an individual’s scanned prints. A pair of pilot projects involving the state and other counties is in progress. Eventually, county officrs will be able to reach all the way to the U.S. Federal Bureau of Investigation AFIS.

It is imperative that field officers understand the limitations of the current fingerprint solution and that they be notified when upgrades are completed. Any tool is only as useful as the humans using it. They must understand what the tool can and cannot do. The training required to use the devices is minimal, but it is nonetheless important to receive it to avoid “tech frustration.” It would be pointless to invest in a technology that officers fail to understand and refuse to use.


The Los Angeles Police Department (LAPD) is credited with bringing the current mobile fingerprinting technology to Los Angeles County. The department acquired a regional grant that was then used to purchase 500 devices and develop a Web page for their officers to use on their MDCs. The LAPD requested that the Los Angeles County Regional Identification System (LACRIS) manage the program within the LASD’s data network. An agreement was worked out in 2005 for distribution of the 500 devices, and within a short time, mobile fingerprinting became a reality. LACRIS is governed by the Remote Access Network (RAN) Board and a countywide technical subcommittee. The subcommittee makes recommendations for biometric solutions to the RAN Board, and the board approves funding for hardware and software purchases that enhance the local AFIS, the Livescan system, and now mobile fingerprinting. The RAN Board’s funding comes from fines and penalties as well as a vehicle registration fee, which is returned to California counties by the state government. The RAN Board committed to providing the hardware at no cost to the law enforcement agencies of Los Angeles County.

Marketing to Agencies

When LACRIS staff began to distribute mobile fingerprint devices to law enforcement agencies in the county, it was imperative to select officers with a desire to experiment with the new technology and to give feedback for improvements. These officers were also asked to share the technology with like-minded officers who would appreciate its value. LACRIS staff felt it was important to gain support from the people who would use it most, providing the initial devices as “loaners” at no cost to the unit or the agency. After 30 days, the device was retrieved with feedback and was lent to another unit or agency. This marketing approach resulted in some excellent suggestions for improvement as well as a clamor for permanently assigned devices.

For agencies with MDCs in their vehicles, it was easy for LACRIS to order the devices, distribute them to those agencies, and provide the agencies’ information technology contacts with configuration instructions. If an agency did not have MDCs, then a PDA or other data transmission device could be provided if that agency agreed to pick up the cost of the data transmission service (approximately $50 per month per device). Very few turned the offer down. The program has expanded to include detective units, gang units, and other specialized law enforcement units.


Los Angeles County has over 4,000 square miles of territory and a population of over 10 million. There are more than 80 cities and numerous unincorporated areas within its borders. The county is patrolled by the LASD, the California Highway Patrol, and over 40 municipal police agencies, including the LAPD and the Long Beach Police Department. Most of these agencies and one federal agency are using the mobile fingerprinting devices provided by LACRIS.

Several success stories have been provided to LACRIS staff: one involves an officer who revealed a rubber display device that looks very much like an actual scanner. As soon as the detained individual saw it, he commented that he had heard on the streets about the device and knew he could no longer fool the officer about his identity. He promptly related his true information before the officer used the “pretend” device.

Another agency had been dealing with a vagrant for a long time without a permanent resolution to the numerous calls it had received. This person had no identification, provided a “generic” name, and had not committed any act that was worthy of anything more than a citation. When provided with a mobile fingerprint device, the agency was able to gain a positive identification and found the individual was wanted on a felony warrant describing the suspect as “armed and dangerous.”

The impact of this new investigative tool in Los Angeles County has been significant. It has provided law enforcement professionals with a piece of equipment almost as important as the portable radio. With the ability to strip away the cloak of anonymity that criminals have used against the community and law enforcement agencies for ages, mobile fingerprint readers have enhanced officer safety as well as the safety of the county’s many communities.


As biometric identification becomes more accepted in the United States for the purposes of banking, computing, facility or vehicle entry, identification documents, and travel, more people will become comfortable with this excellent method of deterring identity theft and securing what needs to be protected from intrusion and larceny. How many judges have heard cases where the individual arrested for a warrant informed the court that it was a relative or a friend who did the misdeed and gave false information to the arresting officer? A fingerprint expert must then be called to court to compare the prints of the original arrest and the individual arrested on the warrant. Mobile fingerprint devices reduce the possibility of this confusing set of circumstances.

These devices can also have a positive impact on securing entry into the United States, to prevent terrorists from gaining access or interdicting them if they are able to get by the first line of defense. Those who protect the United States and its communities, at all levels, will be better able to protect that which needs protection when mobile fingerprint devices are able to reach all state and federal databases and return an identification in a reasonable period of time. Law enforcement professionals who detain deceptive or unidentified individuals need to have this tool and know in short order with whom they are dealing. Mobile fingerprint scanners are now a reality and will be commonplace in the foreseeable future. Many technology experts, academics, law enforcement agencies, and vendors have worked hard to make this technology practical. Who goes there? One finger on the touchscreen is all it takes to find out. ■

Los Angeles County Fingerprint Reader
Success Stories

January 16, 2008:
During a traffic stop, Redondo Beach police officers arrested a driver for a variety of charges, and the suspect asked the officers to release the vehicle to his passenger. The passenger had no identification and gave a false name. After using a mobile fingerprint reader to get a positive identification of the individual, they arrested him for falsely representing himself to a peace officer.

January 23, 2008: Huntington Park police officers stopped a driver who had no license and gave a false name. After positive identification was determined by use of a fingerprint reader, it was determined that the individual was wanted on a no-bail felony narcotics warrant.

January 29, 2008: Huntington Park police officers stopped an individual who gave a false name and date of birth. After using a fingerprint reader to positively identify the individual, officers determined that he had a felony domestic violence warrant. The suspect had fled the country after the warrant was issued and reentered after several years with a different name and date of birth to avoid arrest.

March 20, 2008: An LASD homicide detective reported that during an investigation of a murder in Palmdale, he had arrested two suspects and was actively searching for a third. After about three weeks, the detective got a call from an LAPD officer informing him that the third suspect was in custody. Working near downtown, the LAPD officer had stopped the suspect for possible narcotics activity, and the suspect (who had changed his appearance dramatically) had given a false name. Using a fingerprint reader, the officer was able to take the suspect into custody after acquiring a positive identification and conducting a warrant check, all of which took only a few minutes.

June 17, 2008: Responding to a call about a vandalism in progress, South Pasadena police officers contacted two males on a freeway off-ramp. The responding officers found no evidence of vandalism but felt the two were up to no good. Neither subject had identification, and a fingerprint reader was used in an attempt to gain positive identification. One of the subjects returned with a hit and was determined to have a no-bail warrant; the second subject did not return a hit and was released. During the booking of the no-bail warrant suspect, however, information came to light that the suspect and his associate were involved in a commercial burglary earlier, in the city of Pasadena. Eyewitnesses were able to positively identify the suspect, who was in custody at the South Pasadena Police Department (SPPD). The second suspect became the subject of an SPPD search, and the prints retained in the fingerprint reader will be of vital importance in the eventual arrest of the suspect.



From The Police Chief, vol. LXXVI, no. 6, June 2009. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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