The "Bone Lady" has a face now. Soon, police hope to have a name for her as well. Then detectives can begin trying to track down whoever stabbed her to death perhaps a decade ago and left her to rot in a field in Centreville, where her bones were found in 1993.

Using skills learned years ago in an FBI training academy class, Fairfax County Police Officer Michael F. Nicholson has re-created the chin, cheekbones, nose, eyes and hair of the woman, hoping that the three-dimensional likeness will strike a spark of recognition in someone who knew her.

Fairfax police plan to blanket the state with posters showing the woman's new face; if that doesn't work, they'll widen the net.

Land surveyors came across the woman's complete skeleton, her clothing mostly rotted away, in December 1993 near Sharpsburg Drive--where the Hanna Estates subdivision now sits. A forensic anthropologist from the Smithsonian's Museum of Natural History determined that the woman was white, no more than 5-foot-4, between the ages of 26 and 39, and--at the time of her discovery--dead for at least four years.

The anthropologist also discovered wounds on some of the bones "indicative of a cutting device," Detective Leonard Cordick said, leading police to believe she'd been murdered.

But the case of the Bone Lady, as detectives referred to her, went nowhere. When Cordick was assigned the case late last year, he began looking for new ways to identify his victim.

Then he learned that Nicholson, the department's back-up sketch artist, also had training in skull re-creation. Nicholson, a patrol officer in the Franconia district, had been looking for such a case and quickly accepted the challenge.

Although this is the first such re-creation in Fairfax and believed to be the first in the metropolitan area, it has been done elsewhere, and Nicholson has benefited from the experience of others. Using cadavers, doctors have measured the distance between the skull and the skin at numerous key points in the faces of people of various races and sizes, and have developed fairly precise charts.

Nicholson cut pegs to the lengths specified in the charts and glued them to the Bone Lady's skull. Then he began laying modeling clay between the pegs. The shape of a face quickly emerged.

"You basically put it together like Mr. Potato Head," Nicholson said.

Crafting a nose was more difficult, but the skull provided clues that allowed Nicholson to make a reasonable guess as to what the Bone Lady's nose had looked like. He measured the width of the nasal cavity and added five millimeters to get the width of the nose, then measured the space between the nose and the upper lip to determine the length. The slope of that space also determined whether the nose pointed up or down.

"The way your face is designed is based on the topography of your skull underneath," Nicholson said.

The Bone Lady's most distinctive feature was probably her teeth. Long ago, she had some dental work, Nicholson said, but she clearly had not been back in the dentist's chair for some time. She had a gap between her two front teeth, one of which was crooked and decayed.

"If she's identified," Nicholson said, "it's going to be because of the teeth."

Nicholson portrayed the woman smiling, in order to show off her teeth, which required some study of facial muscles and then some fine-tuning of the chin.

Next came the hair and eyes. Some brown hair was found with the skull, and Cordick said a comb discovered nearby indicated that the woman's hair was fairly thick. He and Nicholson also theorized that her eyes might also have been brown, so Nicholson bought brown "eyes" from a doll store.

At a local drugstore, he bought false eyelashes, which he also used to create eyebrows. He applied makeup to give the clay a skin-like appearance.

Cordick bought a white blouse to drape around Bone Lady's neck, although detectives aren't sure what kind of top the woman actually wore. She appeared to have been wearing shorts and sandals, as if dressed for summer.

"She wasn't a hermit," Cordick said. "She had dental work done. She had jewelry. Somebody knows who she is."

Betty Pat Gatliff, an expert in skull re-creation from Norman, Okla., estimated that three-fourths of them result in an identification. Some happen right away; others take years, she said.

"You just never know," Gatliff said. "It's a combination of art and science."

Anyone with information about the woman is asked to call Fairfax County police at 703-691-2131.

CAPTION: Officer Michael F. Nicholson, left, shows his reconstruction of a human skull found in a Centreville field in 1993. Fairfax County police say the woman may have been slain at least four years before her skeleton was found.