FBI agents probing last year's anthrax attacks today conducted a second search of the Maryland apartment of former Fort Detrick scientist Steven Hatfill.
Hatfill is one of a group of scientists FBI officials have been investigating for months in the probe of the anthrax letter attacks that left five people dead and at least 13 others ill last fall. Investigators first searched Hatfill's home in June.
Law enforcement officials told ABCNEWS that today's search followed newly uncovered information. Five law enforcement vehicles were seen leaving the residence this afternoon.
FBI agents also searched a rental storage shed in Ocala, Fla., that had been rented by Hatfill, as well as at least one other location. The shed had also been previously searched by officials investigating the anthrax attacks.
The researcher has been considered to be "a person of interest" in the investigation, sources told ABCNEWS.
Hatfill has denied that he had anything at all to do with the anthrax attacks and consented to the June search in an effort to clear his name. He said he understood his background and controversial comments made him a logical subject of the investigation.
Agents said they found nothing immediately incriminating in the first search. Officials declined to comment on today's activities.
"We're making progress in the case, but beyond that, I can't comment on ongoing activities of the investigation," said FBI Director Robert Mueller.
Shocking Comments and a Similar Address
Hatfill has worked closely with the military and CIA anthrax experts and has frequently shocked his colleagues with his statements and demonstrations of how easily terrorists could make biological weapons.
ABCNEWS also reported that investigators are intrigued by the fact that Hatfill lived for years near a Greendale Elementary School while attending medical school in Zimbabwe. Greendale School was the phony return address used in the anthrax letters.
In 1999, Hatfill commissioned a study detailing how a hypothetical anthrax attack could be carried out by mail.
Hatfill lost his government security clearance last year, for reasons that remain unclear.
Since the wave of attacks, the FBI has been unable to find out who was behind the anthrax-laced letters. There have been few leads and investigators have admitted that the trail seemed to have grown cold.
Fort Detrick, which also is home to the U.S. Army Medical Research Institute of Infectious Diseases, has anthrax samples, and the FBI is conducting voluntary lie detector tests at the base. Lie detector tests and interviews are also being conducted at Dugway Proving Ground in Utah, where researchers have been developing a powdered form of anthrax for testing biological defense systems. Some 200 people are believed to face the questioning.
Small quantities of anthrax have routinely been produced at Dugway, and then shipped to the Army's bio-defense center at Fort Detrick, Army officials have said. ABCNEWS' Pierre Thomas contributed to this report.