Updated

The FBI is conducting an "evidentiary" search on public land in Frederick, Md., that was the focus of the government's anthrax investigation earlier this year, Fox News has learned.

Frederick, about 45 minutes north of Washington, D.C., was once the home of Steven Hatfill, a 48-year-old biochemist who is considered a "person of interest" in the anthrax case. Hatfill worked at the Fort Detrick Army Medical Research Institute of Infectious Diseases -- the primary custodian of the Ames strain of anthrax found in the letters last fall -- until 1999.

One law enforcement source told Fox News that Thursday's search is indeed related to the Hatfill saga.

The anthrax investigation began last year after letters laced with the deadly bacteria were sent to several Capitol Hill lawmakers and news organizations. Five people died after being exposed to the white powder.

Hatfill is the only "person of interest" whose name has come to public light in the longstanding investigation. Hatfill has vehemently denied any role in the anthrax mailings. His former apartment in Frederick and the storage facilities he rented in Florida have been searched multiple times.

"I am not the anthrax killer," Hatfill said in August as he lashed out against Attorney General John Ashcroft for calling him a "person of interest" in the investigation.

Hatfill allowed the release of the results of his blood test and said he has also offered to compare his handwriting to that appearing on the anthrax letters.

The FBI Baltimore and Washington field offices also issued a statement on Thursday's search. It reads:

"The FBI is conducting forensic searches on public land located within the City of Frederick, Maryland. The searches are in connection with an ongoing criminal investigation. It is important to note that based on water, soil and sediment testing already conducted, there is no indication of any risk to the public health or safety."

Hatfill's publicist, Pat Clawson, told Fox News this was the first he had heard of the situation and that he's looking into the activity. Hatfill has not lived in his Frederick apartment since Aug. 12.

The FBI has said in the past that Hatfill is no more or less important than about 30 fellow scientists and researchers with the expertise and opportunity to conduct the attacks.

Hatfill was fired Sept. 3 from a job at Louisiana State University after the Justice Department sent his supervisor an e-mail ordering that Hatfill be barred from working on department-funded projects.

Fox News' Ian McCaleb contributed to this report.