The guilty guest of the Fingerprint Society unobtrusively pulled on her gloves and carefully polished off any accidental impressions on the glass.

Neither a magnifying glass nor a spray of gray powder was in sight, but a few large, bushy mustaches gave the proper air to the first conference of the Fingerprint Society held in the United States. Over the weekend, about 100 of the society's approximately 1,300 members from six English-speaking countries turned the Quality Inn Embassy Suites Hotel at 20th and N streets NW into the Scene of the Crime solvers.

Harold Deadman (his real name, recalling to mystery fanciers sleuth Lord Peter Death Bredon Wimsey) is a hair and fiber expert with the Federal Bureau of Investigation's crime laboratory. He told how fibers from a bedspread and a rug together with hairs from a family dog--found on two bodies fished out of a river--helped convict Wayne Williams in two of the Atlanta child killings.

The guilty guest looked at the gray hair from her head on her dress, and thought about the thread she'd brushed off.

"A terrorist group," Deadman said, "knew we sometimes comb the pubic hair of victims to obtain hair from the rapists. So they made their victims shower afterward. But they were trapped by hairs extracted from the drains."

Not even criminals who wear gloves are safe from the FBI laboratory, Deadman said. "We can often link up fabric impressions with the suspect's glove."

The guilty guest took off her gloves.

In the case of Jeffrey R. MacDonald, a Green Beret doctor convicted of killing his wife and two daughters at Fort Bragg, N.C., Deadman said MacDonald's story was questioned when investigators found fibers of his pajama shirt in a room where he said he hadn't been.

Fingerprints are not that old as a detective's tool, said Stephen Haylock from the Hertfordshire Constabulary in Welwyn Garden City, England, who with four other fingerprint experts in the constabulary organized the society nine years ago.

Between lectures he said the investigation of fingerprints was "first developed in Buenos Aires, Argentina--I hate to admit--by Juan Vucetica in the 1880s. In Britain and Scotland, fingerprints began to be used as an aid to crime detection in 1901.

"Even identical twins do not have identical fingerprints and sometimes theirs don't even have a family resemblance," he said. "Fingerprints are amazing--no better system could have been created to identify people."

Sam Durrett, of the Secret Service laboratory here, said different countries have different fingerprint standards. "In England, to go into court to identify a fingerprint, they must have 16 points of likeness. In some countries, such as South Africa, only 7 points must be alike. In the United States, it's left to the fingerprint expert."

James Hamilton of the West Palm Beach, Fla., sheriff's office added, "We aren't allowed even one mistake. If we're wrong, we're out."

All seemed to agree that criminals are becoming more sophisticated, wearing gloves at the SOC. (Officers in England who check for clues at the Scene of the Crime are called Socos.) But that doesn't disturb the expert.

John Berry, editor of "The Fingerprint Whorld," noted that the society's newsletter has reported on: techniques for lifting fingerprints off sticky tape, the influence of warts on fingerprints (after the wart, they go back to their original whorl), the use of lasers to raise fingerprints, and how a thumb-marked revenue stamp in India showed a will was forged.

A new system called the Super Glue Fuming System, demonstrated at the conference by the manufacturer, claims to lift prints from plastic bags, cars, gloves, foods, fruit, plants and even people.

Durrett and Deadman said forgers have been detected because they rested their palms on the checks they were signing. And they said footprints are easily detected.

The society gave John Simpson, director of the Secret Service, who welcomed the laboratory experts to Washington, an English bobby's hat, and Stephen Haylock, a chief convention organizer, a Texas Stetson (green with a feather, bestowing on it a Robin Hood air).

"Case Studies of Repetitive Suffocation by Hanging" were explained in detail by Sgt. Peter Banks of the Toronto Police. "The Dermatoglyphics of Sufferers of Down's Syndrome" or why the Simian Crease (a single horizontal line found on the palm in the absence of other lines) is said to indicate the condition, was expounded by Dr. Sarah Holt of Harpenden, England. The role of the Smithsonian's anthropologists in aiding the police was described by T. Dale Stewart of the Natural History Museum.

The guilty guest vowed never to touch anything again.