WASHINGTON -- U.S. investigators on Friday pursued more than 1,000 leads to find those responsible for the anthrax attacks that have killed four and left the nation rattled as new cases of the germ warfare bacteria were reported in Pakistan.
FBI Director Robert Mueller said his team was moving very aggressively to find out who was behind the 16 confirmed cases of anthrax in the United States in the past month. Officials are also looking into whether the anthrax is linked to the Sept. 11 attacks on New York and Washington.
"We are pursuing more than 1,000 leads, including more than a hundred that have taken us overseas. We have conducted more than 2,000 interviews to date in that investigation," he said.
The thrust of the investigation, he said, was focused on Trenton, New Jersey, where three anthrax-tainted letters were mailed that eventually ended up at Senate Majority Leader Tom Daschle's office in Washington and the New York offices of media companies NBC and the New York Post.
"Despite speculation about the possible source of the anthrax and the motive for the attacks, nothing yet has been ruled out and we continue to follow the evidence wherever it may lead," Mueller told a White House news conference.
In a new sign anthrax might be spreading outside the United States, a Pakistani government minister said official tests confirmed at least one suspicious letter received in the country contained anthrax spores.
"Four letters were sent to three places in the last 10 days -- to a national newspaper, a computer company and a bank," Science and Technology Minister Atta-ur-Rehman told CNN. "One case has been confirmed officially, by a government laboratory."
He said the three others had been judged positive for anthrax by a private laboratory but needed to be officially confirmed by the government, which has backed the U.S. war in Afghanistan.
In another potential case of anthrax abroad, State Department spokesman Richard Boucher told reporters traces of bacteria were found on a mail bag sent to the U.S. Embassy in Athens and this was now being tested for anthrax.
"They found a mail bag dirty, funny, stained whatever and tested it. It was the bag itself that was somehow suspicious," Boucher said, adding that some embassy staff had been put on antibiotics as a preventive measure.
Mail bags sent last month to U.S. embassies in Lithuania and Peru have tested positive for anthrax.
In Germany, Health Minister Ulla Schmidt said further tests on two earlier cases of suspected anthrax in the northern German state of Schleswig-Holstein and the eastern state of Thuringia, indicated they were not in fact anthrax.
Schmidt told a news conference that, although final results were awaited, tests on the suspicious packages at the Robert Koch Institute showed they did not contain anthrax as feared.
"The preliminary results here are quite reliable. The final results will be made available Saturday," the minister said.
Bradley Perkins, an anthrax expert with the Centers for Disease Control and Prevention, told reporters in a conference call that the CDC was consulting with a number of countries regarding possible anthrax exposures abroad.
"We have seen a number of anthrax hoaxes on an international level in association with the outbreaks here in the United States," said Perkins, who declined to name which countries had been consulted.
NEW YORK CASE A MYSTERY
In New York, officials said the strain of anthrax bacteria that claimed the latest victim since the outbreak began nearly a month ago, was "indistinguishable" from the bacteria sent to Daschle and various media offices.
Perkins said the CDC's investigators had still not tracked the transmission route of the inhalation anthrax that killed 61-year-old New York hospital worker Kathy Nguyen.
"We do not have any good clues to date and her exposure resulting in inhalational anthrax remains enigmatic at this point," Perkins said.
What is confounding investigators in the New York case is the fact she had no apparent connection to the government and media targets of the mailed anthrax attacks or mail handling.
Police, the FBI and public health investigators have tested the hospital where Nguyen worked and the Bronx apartment where she lived, but have not yet found the source of her infection.
Mueller urged Americans to come forward if they noticed anything suspicious and expressed disappointment more people had not responded to a $1 million reward for information leading to the arrest of those behind the anthrax attacks.
"I want to follow up by urging, in the strongest terms possible, every America to join us in tracking down those responsible for using anthrax to murder Americans," he said.
COMPENSATION FOR FAMILIES OF VICTIMS
On Capitol Hill, legislation was introduced on Friday that would provide federal compensation to the families of those killed by anthrax or allow them to pursue legal claims in federal or state court.
"We need to help families who have suffered so they don't have to worry about the financial future," said House of Representatives Democratic leader Richard Gephardt of Missouri.
Three congressional office buildings are still off limits after anthrax was found in them last month. The U.S. Supreme Court building, which closed for a week after anthrax was found in a mailroom, reopened partially on Friday, but the press and public were not allowed into the building until Monday.
Preliminary tests found anthrax in mailrooms in four U.S. Food and Drug Administration in Rockville, a suburb north of Washington, on Thursday.
An FDA spokesman said those mailrooms remained closed and sealed off on Friday and that conclusive results to determine the contamination were expected later in the day.
About 120 employees of the FDA, which regulates pharmaceuticals, most foods and medical devices, have been prescribed antibiotics as a preventive measure, the spokesman said.
