By DAVID DISHNEAU, Associated Press Writer

HAGERSTOWN, Md. -- Wallace L. Pannier, a germ warfare scientist whose top-secret projects included a mock attack on the New York subway with powdered bacteria in 1966, has died of respiratory failure and other natural causes, his widow said.

He died Thursday in Frederick. He was 81.

Pannier worked at Fort Detrick, an Army installation in Frederick that tested biological weapons during the Cold War and is now a center for biodefense research. He worked in the Special Operations Division, a secretive unit operating there from 1949 to 1969, according to family members and published reports.

The SO unit developed and tested delivery systems for deadly agents such as anthrax and smallpox.

Pannier told The (Baltimore) Sun in 2004 that team members staged their mock attack on the New York subway in 1966 by shattering light bulbs packed with powdered bacteria on the tracks. They tracked the germs with air samplers disguised as suitcases.

"People could carry a brown bag with light bulbs in it and nobody would be suspicious," Pannier told The Sun. After a bulb broke, releasing the powder, "the trains swishing by would get it airborne," he said.

The bacteria used as mock weapons _ Bacillus globigii and Serratia marcescens _ were believed to be harmless but have since been classified as human pathogens.

A year earlier, the SO unit released Bacillus globigii in the air at Washington National Airport and at bus stations in Washington, Chicago and San Francisco, a 1975 Senate investigation found.

Pannier also said he had posed as a fisherman, an air-quality tester and a motorist with car trouble to measure germs leaking from a pharmaceutical plant on the Susquehanna River. The readings would help U.S. spies trying to identify Soviet bioweapons plants.

The SO unit's existence wasn't publicly divulged until 1975. Pannier's wife of 61 years, Betty, said she and their two children knew nothing about the nature of his work before then.

"We didn't know anything for the years he was working. It was not something you spread around," she said.

Pannier was born in Salt Lake City and earned a degree in microbiology at the University of Utah. He served in the Navy during World War II.