"The anthrax investigation has been beset by a number of leaks," said Michael A. Mason, who recently assumed leadership of the probe as head of the FBI's Washington field office. "I think that's unfortunate."
Hatfill, a former government scientist, has denied any role in the 2001 attacks that killed five people and sickened 17 others. He has filed a lawsuit against Attorney General John Ashcroft and the FBI accusing the government of "a campaign of harassment" and unfairly singling him out.
Hatfill claims that, by labeling him a "person of interest" in the case, Ashcroft and other federal authorities have destroyed his reputation and ruined his job prospects.
The lawsuit also states Hatfill is under constant surveillance, leaving him unable to freely talk to his girlfriend, family or friends.
Mason told reporters Monday that giving out "person of interest" information publicly "leads to the same sort of calamity" that occurred when Richard Jewell was wrongly accused in the 1996 bombing at the Atlanta Olympics.
"It's very hard to take that back if you're wrong," Mason said.
Still, Mason said that Ashcroft may have had little choice in naming Hatfill because his name had already been leaked to the media.
Law enforcement officials have said Hatfill is not a suspect and that no evidence links him to the letters.
Hatfill once worked as a researcher at the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick in Frederick, Md. The facility housed the strain of anthrax found in the envelopes sent to the victims.
Since June 2001, investigators have searched Hatfill's Frederick apartment multiple times, as well as a storage unit in Florida and his girlfriend's resident. Nothing linking him to the attacks has been found.
Last May, Hatfill was struck by a vehicle being driven by an FBI employee who was tailing him in Washington's Georgetown neighborhood. Hatfill was not seriously injured.