Despite enormous strides in DNA analysis and the high-tech forensics glamorized on such television shows as "CSI," it is the fingerprint that routinely allows investigators to solve crimes.
"Basically, what you're doing is taking a time-honored way of solving crime and applying 21st century technology to it," FBI spokesman John Iannarelli said in Washington.
For simplicity and accuracy, police say, nothing has taken the place of fingerprinting. With its unique combination of loops, arches and whorls, the fingerprint indisputably places a suspect at a crime scene -- or exonerates the innocent.
Moreover, advances in technology allow police to lift prints from the trickiest of surfaces, then match them instantly to a vast database with links spanning the globe.
The FBI's Integrated Automated Fingerprint Identification System is the world's largest, with more than 44 million prints on file.
Authorities investigating the fatal shooting of 10 people in the Washington area were able to identify John Lee Malvo, 17, as a suspect because his fingerprint was found on a weapons magazine near a fatal liquor-store robbery in Montgomery, Ala. Police linked the robbery and Washington area shootings through a rifle they said was used in both places.
Malvo's prints were in the FBI database for unrelated reasons. He was fingerprinted after he and his mother were arrested by the Immigration and Naturalization Service last year for entering the country illegally.
Fingerprints help solve crimes in several ways. Often, they allow investigators simply to confirm a hunch, said Tony Moss, a fingerprint examiner at the Orange County Sheriff's Office. Cops have a suspect, and they have prints from a scene. Match the suspect's fingerprints to those found at the scene, and a case is made.
Where computer-based databases prove invaluable is in tying a perpetrator to a crime scene when detectives have no idea who committed the crime. They break cases that would have been impossible years ago without manually combing through thousands of sets of prints, looking for a match.
In some cases, the technology is used to solve old crimes.
Earlier this year, Michigan authorities charged a former Orlando Naval Training Center sailor in the 1986 rape and slaying of a University of Michigan music professor. Police said they linked Jeffrey Wayne Gorton to the killing after fingerprints from the scene matched those in the state's database. Gorton also was convicted in the 1991 rape and slaying of a Northwest Airlines flight attendant near Detroit's Metropolitan Airport.
His prints were in the system because of a 1983 conviction for stealing women's undergarments in Orange County, Fla.
Also this year, the Volusia County (Fla.) Sheriff's Office used the Florida Department of Law Enforcement's fingerprint database to solve a 12-year-old sexual assault case. Sheriff's investigators charged Billy Dukes, 44, in the 1990 rape and kidnapping of a DeLand woman after his fingerprints were matched to those found in the woman's car. Dukes was in prison on an unrelated conviction.
Fingerprint technicians were looking over prints from cold cases when they got a hit on Dukes. Armed with the new information, they tracked down the victim, now living out of town, and she identified Dukes from a photo lineup.
"It's cool. This print had just been sitting in a box. We plugged it in [to the computer], and boom, we hit it," said Larry Lewis, technical services manager for the sheriff's office.
The human element is still crucial. Computer databases offer the best set of matches to a submitted fingerprint. Experienced print analysts then use their eyes to confirm a match.
Lt. Dale Coleman of the Oviedo Police Department said fingerprints are valuable not just in breaking a case, but also in prosecuting it.
"DNA is very helpful, but beyond what most people understand," Coleman said. "A fingerprint -- everyone has one, and they can see it on their own hand. It's very easy on the lay person to understand."
The conventional wisdom is true: No two people have been found to have identical prints. Not even DNA has that distinction, authorities say. DNA testing cannot tell identical twins apart, but their fingerprints are unique.
As a crime-fighting technique, fingerprinting grew in fits and starts until 1905, when Scotland Yard used a thumbprint to solve the bloody murder of two shopkeepers in Britain. Little other evidence was found at the scene.
Not everyone was sold on the "new" technology. The head of the French Identification System scorned the use of fingerprints, preferring the method of measuring the unusual dimensions of a person's body parts to establish an ID.
Consequently, the theft of Leonard da Vinci's "Mona Lisa" in 1911 went unsolved for years, despite a set of greasy fingerprints found on the famous painting's glass case.
A landmark case took place in Chicago that same year, when Thomas Jennings became the first person convicted of murder in this country based on fingerprint evidence.
Jennings was arrested when he was found prowling with a recently fired revolver. His fingerprints matched those discovered on the freshly painted porch railing of the home where an intruder shot a man to death.
The case held up on appeal and set a precedent for relying on prints.
The practice of using powder and tape to lift prints from a crime scene has remained largely unchanged through the decades, but criminologists have refined techniques so that evidence can be gathered from a variety of surfaces.
At the Orange County Sheriff's Office complex, crime scene supervisor Susan Gattis uses a variety of powders and chemicals to obtain the best available print.
Fingerprints have been lifted off many surfaces, ranging from a concrete wall to a victim's skin, Gattis said.
One of her favorite gadgets is a vacuum chamber in which evidence and a compound similar to Super Glue are placed. The chamber draws out oxygen, turning the glue into a vapor that adheres to the ridges of fingerprints on the evidence.
"It basically Super Glues the evidence," Gattis said.
Criminals can be remarkably sloppy about leaving prints, but even when they do take measures to hide their trail, this can be turned against them.
Gattis said thieves have used tissue to wipe away prints, then left their prints on the tissue.
Moss recalls a case in which someone used rubber gloves to commit a crime, but left the gloves behind. A print was obtained from the inside of a glove finger.
Computers also allow crime-fighters to make better use of prints. Bob Johnson, a lab technician with the Orange County Sheriff's Office, uses software to enhance the image of a crime-scene print without altering it. With a click of the mouse, he can sharpen the print's outline, or change background colors to provide better contrast.
Johnson, a former New Orleans police captain, has worked with fingerprints off and on for three decades. He explains their popularity this way: "It's tough to explain your fingerprints' being somewhere they're not supposed to be."