The justices did not comment Monday in turning down Hatfill's appeal of a unanimous ruling by the 4th U.S. Circuit Court of Appeals, based in Richmond, Va. A three-judge panel affirmed a lower court's dismissal of the libel claims on the grounds that Hatfill is a public figure and failed to prove that columns written by Nicholas Kristof were malicious.

Circumstantial evidence led the FBI to suspect Hatfill was involved in the anthrax attacks that killed five people and sickened 17 just weeks after the Sept. 11 terrorist attacks. Then-Attorney General John Ashcroft publicly identified Hatfill, who worked at the Army's infectious diseases laboratory at Ft. Detrick, Md., from 1997 to 1999, as a "person of interest" in the investigation.

In June, the Justice Department agreed to pay Hatfill $5.8 million to settle a lawsuit claiming officials violated his privacy rights by speaking with reporters about the case.

No one has been charged in the attacks, although the government now believes another Army scientist, Bruce Ivins, was responsible. Ivins killed himself in July.