The FBI has admitted little progress has been made in the anthrax attacks investigation as letters with the spores emerged in Germany, Pakistan and India.
The detective agency's director Mr Robert Mueller appealed yesterday for renewed help from the public as he admitted there was nothing substantial to report in progress in the probe.
He spoke as the attacks appeared to spread, with a letter to a person in the eastern German town of Rudolstadt testing positive for the deadly spores and anthrax-laced letters were found at a newspaper in Pakistan and an Indian politician's office.
Mr Mueller said: "Despite speculation about the source of the anthrax and possible motives for the attacks, nothing yet has been ruled out."
Fears have been fuelled in America of widespread infection after a woman in New York who had no apparent contact with an anthrax-laced letter died and the spores were found in two midwestern states.
The only letters to be discovered were to Senator Tom Daschle in Washington, to broadcaster NBC in New York and the New York Post newspaper.
Mr Mueller said: "We are currently looking closely at the recent fatality in New York to see what that might tell us, but it is too early to reach any conclusion."
Mr Mueller called for more help from the public, saying has surprised how little response there had been to a million-dollar reward put up for information leading to the perpetrators.
"We had hoped that the one million dollar reward announced by the FBI and the United States Postal Service would encourage many more of our fellow citizens to step forward with important information," said Mr Mueller.
AP