One new case of inhalation anthrax in a New Jersey postal worker, and new reports of minor traces of anthrax in the mail areas of both the Justice Department and the State Department, ensured yesterday that the drip-drip anthrax war remained centre stage in US preoccupations.
The anthrax threat also forced the Supreme Court to meet elsewhere yesterday for the first time in its building's 66-year history. The building was closed after anthrax was detected on Friday at a remote mail-handling area.
A spokesman for the Centers for Disease Control and Prevention stressed that the New Jersey case was not a new instance of the disease, but one that had been listed as suspected anthrax.
Laboratory tests confirmed the diagnosis on Sunday, he said. Another New Jersey post office, at Princeton, has been contaminated causing workers to worry about the extent of cross-contamination from letters which appear to have passed through the Trenton office. There are also fears of as-yet-undiscovered contaminated letters.
Speaking on TV over the weekend, the White House chief of staff, Mr Andrew Card, said officials must remain vigilant.
"There may be other letters that are stuck in the system," he said.
The postal service said it now has 23 workers in the Washington-Baltimore area and three in New Jersey hospitalised with suspicious symptoms.
Some 13,000 employees are now receiving precautionary antibiotics.
The investigation, unlike that of the attacks on September 11th, appears to have few leads.
On Friday, the President's spokesman, Mr Ari Fleischer, said the level of sophistication required to produce the highly volatile, and hence infectious, Daschle sample suggested a scientist with a PhD in microbiology working in a well-equipped microbiological laboratory. With 30 to 40 such laboratories in the US alone, early speculation that the resources of a state-level actor were needed has been dispelled - speculation that pointed firmly at Iraq.
Over the weekend there was further speculation that the anthrax contained a chemical called bentonite, seen as a signature chemical for Iraqi production.
But yesterday Mr Fleischer said that tests showed an absence of aluminium in the anthrax, and hence ruled out bentonite.
The expertise assessment has also strengthened the view of many in the FBI and CIA who believe that a home-grown terrorist may be responsible, linked only to Osama bin Laden by opportunism at a time when national vulnerability is at its highest.
They are looking not just at possible Muslim extremists but their unlikely allies on the violent neo-Nazi or survivalist right.
One group, Aryan Action, praises the September 11th attacks on its web site and declares: "Either you're fighting with the Jews against al-Qaeda, or you support al-Qaeda fighting against the Jews."
White supremacists have been linked with anthrax in the past, but not in relation to an attack.
Mr Larry Wayne Harris, an Ohio microbiologist and former member of the Aryan Nations, was convicted of wire fraud in 1997 after he obtained three vials of bubonic plague germs through the mail.
He was arrested the next year near Las Vegas when the FBI acted on a tip that he was carrying anthrax.
However, agents found only harmless anthrax vaccine in the trunk of his car.
To date 13 cases of anthrax have been confirmed. Three people have died, an editor in Florida and two postal workers in Washington, all having contracted the inhalation variation. Five more are ill with the latter, while five others have cutaneous [skin] anthrax.