For more than a century, the fingerprint has been the quintessential piece of crime scene evidence. But fingerprints are only a tiny part of the story. All of a person's "friction ridged skin" is distinctively patterned: soles, palms and even the writer's palm, as the outer side of the hand is called.

Surveys of law enforcement agencies indicate that at least 30 percent of the prints lifted from crime scenes from knife hilts, gun grips, steering wheels and window panes are of palms, not fingers.

That is why in April, the New York Police Department began having prisoners place their whole hand, not just their fingertips, on the glass platen of a scanner when their prints are captured. Beginning next month, the department will be able to do computerized matches of the 100,000 palm prints it has already collected. As the database grows, it will become one of the largest of its kind.

The cost of image storage and computerized matching equipment once limited database entries to fingertips. But technological advances have enabled a growing group of law enforcement agencies across the country about 30 so far, based on information provided by companies that sell the systems to build their own palm databases. The Los Angeles metropolitan area began using one last month. Miami, Palm Beach, Philadelphia and Indianapolis have created databases this year. And Harris County, Tex., which includes Houston, has a database in the works.

Using palm prints for identification concerns some defense lawyers, who point out that the reliability of fingerprint matching has come into question in the courts in recent years, and that there is even less data available on palm prints. But proponents of using palm prints note that none of the dozens of fingerprint challenges have succeeded.

There is as yet no national repository for palm prints, but the Federal Bureau of Investigation is currently assessing three systems, including one by Sagem Morpho, the biometrics company based in Tacoma, Wash., that designed New York's database and scanners.

Police departments have long taken palm prints with ink, either routinely or case by case. But computerized databases are expected to exponentially increase the number of matches, as they did with fingerprints. Since 1999, when the F.B.I. computerized its fingerprint database, its crime lab has matched about 1,200 crime scene prints, more than five times the number found in 15 years of laborious manual matching, said Stephen Meagher, the head of the lab's latent print operation.

Though statistics on palm data are hard to come by, the law enforcement agencies that have begun using palm databases have reported good results, said Steven Nash, the chairman of the International Association for Identification, adding that many detectives have run prints from older cases. "They are getting hits on previously unknown and unused latent palm prints that are just lying around doing nothing," he said.

One city that has kept a count is Indianapolis, which has come up with a match in 15 percent of its palm searches, according to statistics provided by Identix, the company that created the system. That is not as high as the 31-percent success rate for the city's fingerprint database. But there are only 16,000 palms in the system thus far, compared with 300,000 fingerprint records.

Investigators are hopeful that the palm technology will help solve more property crimes, many of which depend on fingerprints for resolution. Property crimes nationally are solved at a much lower rate than violent crimes 16.5 percent compared with 46.8 percent, according to F.B.I. statistics.

"It's worth every cent, and especially the victims are going to think that," said Sgt. Donna Wright, an investigator for the Palm Beach County Sheriff's Office who has gotten two hits so far from running palm prints on burglaries. "A burglar goes out and probably commits 300 or 400 crimes a year."

Police Commissioner Raymond W. Kelly of New York said through a spokesman, "This is cutting edge technology that gives our detectives another powerful tool to help solve crimes."

At the police academy in Manhattan last week, Officer Maximilian Velazquez stood by a row of new ILS2 palm scanners, each one about the size of a video arcade machine. The department has 83 of what will eventually be 140 scanners at least one for every precinct, courthouse, transit and housing bureau. When officers book an arrest, the machine prompts them through the print collection process. Fingers, thumbs and palms are positioned on the glass in sequence, as the print images appear, much magnified, on the screen.

The best thing about the new machines, said Officer Velazquez, a coordinator in the computer training unit, is that it rejects faulty prints, gently scolding with messages like "finger rolled too slowly" or "finger shifted vertically."

Just as with the old scanners, each set of prints is transmitted directly to the department's database, where the computer brings up possible matches and a fingerprint examiner at Police Headquarters makes the final determination as to whether it is a hit. With the new database, examiners could conceivably make a match from a fraction of a palm print smaller than a dime.

While a few departments have had palm print databases for several years, New York will be one of the first to have a system that uses live, or inkless, scanners that feed directly into the database, said James E. Simon, the head of the N.Y.P.D.'s Central Records Division. (The department has used live scanners for fingers since 1997.)

While the scanners offer images of astonishing resolution, significant chunks of the fingerprint record-keeping system seem stuck in the dark ages. For instance, the city scans in fingerprints and transmits them to the state, which then makes hard copies and mails them to the F.B.I., which rescans them into the national database.

When three people were murdered in an apartment over the Carnegie Deli in Manhattan in 2001, the police ran a check on one suspect and learned that he had been arrested in Georgia. The palm print card from that arrest was carried to New York by a special courier, said Barbara Thompson, a spokeswoman for the Manhattan district attorney, Robert M. Morgenthau. The card matched a palm print found on duct tape used to bind the victims.

The palm database is part of an upgrade to the New York Police Department's print archive, including the digitization of two million ink fingerprint cards dating back to 1981, which were not searchable by suspect or arrest number. The database project will cost $5.9 million over the next five years, Mr. Simon said. The 140 new scanners will cost an additional $5.8 million.

Why undertake a project like this when DNA profiling is advancing so quickly? "DNA is subject to destruction," Mr. Simon said, adding that 340 World Trade Center victims were first identified by fingerprints, and 50 of them remain identified only by fingerprints.

Some defense lawyers raise the same objections to palm print identifications as they have to fingerprints. "The criminal courtroom is no place to experiment with a scientific method that may incriminate someone," said Steven D. Benjamin, the co-chairman of the forensic evidence committee of the National Association of Criminal Defense Lawyers.

But even if the scientific basis of palm matching is questioned, Edward J. Imwinkelried, an evidence expert and professor at the School of Law at the University of California at Davis, said that judges will most likely still admit it as "nonscientific expertise," just as they have sometimes done with fingerprints.

Mr. Meagher, of the F.B.I. crime lab, said that the scientific underpinnings of palm print identification are the same as those of fingerprint identification, and he does not expect either to be successfully challenged. "It wouldn't surprise me if four or five years from now we were having the same conversation about adding footprints" to the database, he said.