Detective Gary Irwin, an investigator in the Montgomery County police's pedophile section, sheds his badge and gun when he visits the homes of recently abused children to get them to describe their attackers.

Irwin, the department's only forensic artist who does hand-drawn sketches, relies as much on interviewing skills as he does on his steady hands and talent.

"Your sketch is only as good as your witness," Irwin said. "Your sketch is only as good as your artist."

In recent years, however, a new truism has become part of the field of forensic art: Your sketch is only as good as your software.

Montgomery detectives now do most of their work creating likenesses of suspects using computer software that allows them to assemble portraits by pulling together a set of human features and accessories that can be tweaked, trimmed, darkened and softened with a few clicks of a mouse. And because each facial feature is ready-made from a computer database, even the least artistically adept detectives can create an image.

These images, called composites, are an increasingly useful tool in an age in which law enforcement officials can distribute a sketch to the public with the help of the Internet, the Amber Alert system, 24-hour cable news channels and widely watched crime television shows such as "America's Most Wanted."

"Prior to a computer age, you'd have to hand-deliver these," said Deborah Haba, a detective in Montgomery's robbery division, who has been with the department 17 years and started creating computer-generated composites in 2001. "The immediacy of putting out an image of a suspect is extremely important because the longer you delay, the less likely it is people will be interested."

Haba is one of three Montgomery officers who create computer-generated composites regularly. She has always enjoyed drawing but only recently came to think of herself as an artist.

"I'm an artsy-fartsy person who was never allowed to be an artsy-fartsy person because it wasn't cool when I was in high school," Haba said. Now she frequently finds herself prodding victims and witnesses of crimes for detailed descriptions of suspects, often working against tight deadlines.

Last spring, Haba created a composite of a man suspected of killing gas station clerk Syed Rizvi, 55, in March in the Aspen Hill area of Silver Spring. Hours after the homicide, the department released a computer-generated image of the killer, a black man in his mid-twenties who had braided shoulder-length hair and was wearing sunglasses and a black knit cap. He remains at large, and detectives hope the composite will lead to an arrest.

"When it's a serious case like this one we try to do it as quickly as we can," Haba said.

Irwin, 44, generally has to wait a bit longer to conduct interviews because most of his cases involve children who are deeply shaken after being assaulted. He builds rapport by conducting interviews in a non-threatening environment -- often at the kitchen table of the child's home.

Irwin drew a composite of Jorge Rivera-Aleman, 39, who earlier this year pleaded guilty to the November 2004 rape of a 13-year-old girl in Silver Spring. The sketch, culled from a lengthy interview with another victim he was suspected of assaulting, strongly resembled Rivera-Aleman, who was arrested in January attempting to break into a Silver Spring home. The only inaccuracy in the composite was the man's hair; he might have been wearing a wig during the assault, Irwin said.

A more recent case involved another 13-year-old victim who was fondled in July by a man who stuck his hand through a car window while the girl's mother had stepped into a 7-Eleven store in Germantown. When the suspect, Federico Monzon-Santana, 30, turned himself in to police, the lead detective in the case recognized him immediately because he had seen Irwin's composite.

In that case, Irwin, who has been doing sketches for the department for three years, interviewed the victim and her mother separately. They gave him similar descriptions but differed on whether the suspect parted his hair on the right or the left. Irwin went with the victim's account, which turned out to be correct.

Not all composites lead to arrests, and they are generally not enough to demonstrate probable cause that a person has committed a crime. But they are an invaluable tool for police because they can lead to statements and physical evidence that provide enough information for an arrest. They also reassure victims and their families, Irwin said.

"It tells the victim and their family that police are exhausting all possibilities," he said.

Composites -- both hand-drawn and computer-generated -- take anywhere from two to four hours to create. Forensic artists ask open-ended questions about such features as the shape of a face, skin tone, hair type, eye color and distinct characteristics of the nose and ears. After composites are created, witnesses and victims can offer critiques and suggest changes.

Other Washington-area jurisdictions have their own methods of creating composites. Fairfax County police do most of their composites by hand, and D.C. police have a civilian employee who does them on a computer. Smaller forces, such as the Anne Arundel County Police Department, sometimes use computers to create composites but favor the old-fashioned method.

"We prefer hand sketches," Lt. David Waltemeyer, an Anne Arundel police spokesman, said, adding that the work is often given to a forensic artist from the Baltimore police.

Forensic artist and historian Karen Taylor, of Austin, Tex., said the earliest documented forensic composite was done by Scotland Yard, London's police department, for an 1881 murder.

One of the first high-profile cases in the United States in which a suspect's composite played a prominent role was the 1932 kidnapping of aviator Charles Lindbergh's 22-month-old son. The child was found dead 10 weeks after being seized. Bruno Hauptmann was convicted of kidnapping and murder in the case and was executed in 1935.

More recently, a hand-drawn composite helped lead to the arrest of Oklahoma City bomber Timothy McVeigh. A sketch was drawn by an FBI agent based on interviews with witnesses who had seen McVeigh at a Ryder rental dealership. Motel employees in Junction City, Kan., said the image strongly resembled a former guest, McVeigh, who was later found to be in a Perry, Okla., jail.

The shift toward computer-generated composites bothers some in the field who fear the technology will be used by people who are not formally trained or visually adept. But Taylor, who worked for the Texas Department of Public Safety for nearly two decades and now teaches forensic art to law enforcement officials around the country, isn't disturbed by the trend. She said computer-generated composites are a valuable tool.

"The most important factor in the composite is the interviewing skills," Taylor said. "They are more significant than whether you are doing computer-generated or hand-drawn sketches."

Taylor said most police departments don't invest enough resources to train and retain forensic artists.

"High-quality training in this field is extremely rare," she said. "I would like to think that anyone who gets involved in forensic art considers it a lifelong training."

Haba said the county police department's composites are bound to improve if the agency invests in better software for its forensic artists. The composite database she uses lacks important elements, such as features of Asian people and a broad selection of accessories such as sunglasses and hats.

"In my database, the headwear looks like it's from the 1970s," she said. "I had to create my own do-rags because we don't have do-rags in the database."

While most Montgomery County police sketches are computer-

generated, Detective Gary Irwin, left, still does hand-drawn sketches. The Anne Arundel County police still prefer hand-drawn sketches too, a spokesman said.A computer-generated sketch, left, by Detective Deborah Haba, compared to a photo of robbery suspect Darrell Glascock.Detective Deborah Haba, above, with a computer sketch she made of a robber. At left, Detective Gary Irwin, who prefers drawing sketches by hand, shows off his concession to modern technology: an electric eraser.