The FBI searched the home of a researcher next to Fort Detrick, who may have had access to anthrax while doing work for the Army base, a law enforcement official said Tuesday.

The researcher agreed to the search in hopes of removing himself from any possible suspicion, according to the official, who spoke on the condition of anonymity. It was unclear whether the researcher was a federal worker at Fort Detrick or a worker under contract with the Army base.

"This was a consensual search for which the only qualification was potential access to anthrax," the law enforcement official said. The official said the search was not unusual in the FBI's hunt for a suspect for last year's anthrax letter attacks.

Fort Detrick, which also is home to the U.S. Army Medical Research Institute of Infectious Diseases, has anthrax samples. The FBI is conducting voluntary lie detector tests at the base.

A man who identified himself only as an FBI agent kept reporters away Tuesday night from the entrance to the Detrick Plaza Apartments, where the search was being conducted. The civilian complex shares a barbed-wire fence with the Army post.

Aerial photographs showed a white truck parked close to an entrance of one of the apartment buildings and a pile of full black trash bags nearby.

Angelica Aguilera, who lives at the complex, said there were several FBI agents inside the building when she came home. She said she did not know exactly where in the building the agents searched.

At the conclusion of the search, no arrests were made.

The search underscored the FBI's attempt to find a suspect in the deadly anthrax letter attacks last fall. Five people died in the attacks, and at least 13 others contracted and recovered from either the skin or respiratory form of the disease.

The investigation into who sent several anthrax-laced letters last year has produced few leads and some investigators acknowledge the trail is growing cold. The government has begun a strategy of focusing on possible sources of anthrax and casting a wide net, rather than identifying suspects from the few clues gained from the letters.

Lie detector tests and interviews are also being conducted at Dugway Proving Ground in Utah, where researchers have been developing a powdered form of anthrax for use in testing biological defense systems, military officials have said.

The Army said recently that small quantities of anthrax have routinely been produced at Dugway, and then shipped to the Army's biodefense center at Fort Detrick.

Since the attacks, security at Fort Detrick has come under fire.

One former researcher at the infectious-disease center there has said nothing would have prevented workers from removing deadly germs from the labs.