About 100 federal agents, including divers, continued searching Friday in Maryland's woods and ponds for evidence in last year's anthrax attacks, not far from the former home of Dr. Steven Hatfill, the ex-Army scientist the government has labeled a "person of interest" in the case.

The FBI search is taking place on wooded public land several miles from the Frederick, Md., apartment Hatfill once occupied. Officials confirmed that the search, begun Thursday, was tied to the anthrax investigation.

Nancy Poss, a Frederick city spokesman, said after local officials were briefed about the probe Friday that the FBI is "seeking evidentiary items" and not looking for anthrax spores. Poss said two scientists on the investigative team regularly monitor water in the area for possible contamination.

FBI agents closed off a 1-mile section of an icy two-lane road in the Catoctin Mountains at a site about 10 miles south of the Camp David presidential retreat. Two Justice Department officials, speaking on condition of anonymity, said divers were searching at least one pond, but they would not say what evidence was being sought.

The investigation is expected to continue through Wednesday, Poss said.

In a statement, the FBI said it was conducting "forensic searches on public land" and stressed that previous water, soil and sediment tests had ruled out any anthrax threat to public health or safety.

Hatfill, whose former apartment has been searched at least three times, worked until 1999 for Fort Detrick's Army Medical Research Institute of Infectious Diseases in Maryland. It is the primary custodian of the virulent Ames strain of anthrax found in the anthrax letters.

Hatfill has denied any involvement in the October 2001 anthrax attacks. Five people died and 18 others were infected when letters containing the deadly spores were sent to government and news media offices in Washington, New York and Florida. Thousands more were put on antibiotics as a precaution.

Hatfill has said the Justice Department's scrutiny has destroyed his career and left his personal life in turmoil. His friend and spokesman, Pat Clawson, denounced the latest FBI search.

"The FBI can search the planet until hell freezes over but it will find that Steve Hatfill was never involved in the anthrax attacks," Clawson said.

The search came as Assistant Attorney General Daniel J. Bryant, in a letter to Sen. Charles Grassley, said the "person of interest" term originated with unnamed FBI sources as speculation swirled in the media and on the Internet earlier this year that Hatfill might be a suspect.

The phrase, Bryant said, was intended to "deflect media scrutiny from Dr. Hatfill and explain that he was just one of many scientists" being questioned by the FBI in the anthrax probe. That status has not changed, officials said.

The Justice Department letter, released by Grassley, R-Iowa, acknowledged there is no formal definition for "person of interest," but said it is a commonly understood term for "an individual whom law enforcement officials seek to question in connection with a particular matter."

In a statement, Grassley said the letter shows use of the term to describe Hatfill is unprecedented and not supported by any formal policy or evidentiary standard.

"Government agencies need to be mindful of the power they wield over individual citizens, and should exercise caution and good judgment when they use that power," said Grassley, a senior member of the Senate Judiciary Committee.

Clawson said the letter shows that the department "makes up the rules as it goes along and is utterly shameless about trampling on due process and civil rights."