Investigators' search for clues comes up empty

WASHINGTON -- They've hunted for clues in her Bronx apartment and the hospital where she worked, scoured phone bills and retraced her steps. But health investigators, who probe medical mysteries much as police try to unravel crimes, have come up empty.

The disease investigators are trying to find out how Kathy T. Nguyen was exposed to anthrax. So far, they're finding traditional techniques are not enough to solve a case in which the dead woman had few friends or family to help explain where she might have encountered the deadly spores.

"There often are cases that really are puzzlers, that don't look at all like anything you've had before," said Dr. D.A. Henderson, a bioterrorism adviser at the Department of Health and Human Services.

Last week, investigators appealed to the public for help. They've hung posters along her subway route asking anyone who recognizes Nguyen, a 61-year-old Vietnamese immigrant, to tell them what they know. They also are checking samples from air filters at stations between her home and work, looking for lurking anthrax.

Like detective work

It can take years before answers appear, said Dr. Stephen B. Thacker, who runs the Epidemic Intelligence Service, for the Centers for Disease Control and Prevention in Atlanta.

In the case of Nguyen, investigators know what killed her -- anthrax -- but they don't know how she encountered it.

Each inquiry begins by reconstructing the places a victim visited and the people she saw. If she played bridge every Tuesday, investigators can examine the church where the game was played. If she was friends with a postal worker, maybe she stopped by his office for a visit.

"You try to find every clue," Thacker said. "It's very much like detective work."