The FBI is denying a newspaper report that it is focusing on a former government scientist as the chief suspect in last fall's anthrax mailings.

The Washington Times reported in its Monday edition that the unnamed scientist formerly worked at the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick, Md., where weapons-grade anthrax is stored.

The suspect was twice fired from government jobs, the Times reports, and made threats to use anthrax after the Sept. 11 attacks. He still lives and works in the Washington area, the paper says, and he has been interviewed by the FBI several times and his house has been searched.

A law-enforcement official told Fox News Monday that "it is not accurate ... that the FBI has identified a prime suspect in this case."

The official dismissed the Times story as "overplayed" and "laughable."

The FBI ruled out a foreign origin for the anthrax months ago and narrowed the search to an American scientist familiar with and with access to U.S. military supplies.

The Times says law-enforcement officials and biomedical experts told them the suspect emerged after more than 300 interviews over five months with people involved in the government's anthrax program.

Barbara Hatch Rosenberg, a microbiologist at the State University of New York who leads the bioweapons panel of the Federation of American Scientists, told the Times that there had been a "short list of suspects" for some time and that "a particular person ... a member of the biochemical community" stood out.

FBI Assistant Director Van Harp told the 40,000 members of the American Society for Microbiology last month that it was "very likely that one or more of you know this individual."

Five people died as a result of the weapons-grade anthrax mailings in October and November — Robert Stevens, a tabloid newspaper photograph editor in Florida; Thomas Lee Morris and Joseph Curseen, two Washington-area postal employees; Kathy Nguyen, a hospital stockroom worker in New York City; and Ottilie Lundgren, an elderly woman in Connecticut.

All died from inhaled anthrax infections, the most dangerous form of the disease.

The anthrax spores were sent to the offices of American Media in Delray Beach, Fla., where Stevens worked and which publishes the National Enquirer, the Star and the Weekly World News; to the Capitol Hill offices of Sens. Tom Daschle, D-N.D., and Patrick Leahy, D-Vt.; and to various media organizations and personalities in New York City, including CBS Evening News anchorman Dan Rather, NBC Nightly News anchor Tom Brokaw, The New York Times and the New York Post.

About a dozen people, mostly postal workers and media employees, were infected with non-life-threatening skin-borne forms of anthrax. A second employee of American Media in Florida contracted lung-based anthrax but survived.

Nguyen, the New York hospital worker, and Lundgren, the Connecticut woman, are thought to have never come into direct contact with any anthrax-laden letters, but instead to have been infected by spores that rubbed off contaminated letters onto other pieces of mail.

The anthrax powder sent to Sens. Daschle and Leahy was extremely concentrated and had been treated to eliminate static charges, enabling it to float freely in the air. Genetically, it belonged to the Ames strain, the most common American laboratory variety. It also contained a form of silica common in U.S. varieties, but did not contain bentonite, which is more often used by foreign labs, including those in Iraq, the Times reported.

The Justice Department is offering a $2.5 million reward for information leading to the arrest and conviction of those responsible for the anthrax mailings.

Fox News' Paul Wagenseil contributed to this report.