The State Department prepared to pick through three weeks' worth of unopened mail, searching for an anthrax-tainted letter they believe passed through the department's mail center but has yet to be discovered. 
It wasn't clear why that search had not yet begun, given that health officials long have suspected that an undiscovered letter was almost certainly to blame for a State Department mail handler becoming infected with the inhalation anthrax. This rare and dangerous form of the disease requires contact with a substantial number of spores. 
State Department officials said Tuesday that they became convinced that such a letter passed through their Sterling, Va., mail facility after anthrax was found in eight spots there. 
"We have to assume that, one, there is a contaminated letter of some kind in our system, and second of all, that we will eventually find it in one of these mail rooms or pouch bags," State Department spokesman Richard Boucher said Tuesday. 
For its part, the FBI said it didn't press for a quicker search because it doubts that a letter will be found, an assumption disputed by both the State Department and the CDC. 
Two weeks ago, the FBI came under fire from House lawmakers who questioned why it took the bureau so long to begin sorting through unopened congressional mail. In that case, the issue was whether regular mail had been contaminated by touching an anthrax-filled letter addressed to Senate Majority Leader Tom Daschle. 
On Tuesday, the last of six people to survive inhalation anthrax came home after 25 days in a suburban Washington hospital. Leroy Richmond, a postal worker at the city's contaminated central facility, said he was grateful to doctors who began treating him for anthrax even before it was confirmed. 
At the State Department mail facility, testing found anthrax in eight spots, including six on a single automated mail sorter. That suggests that a letter containing a substantial amount of anthrax passed through it, Boucher said Tuesday. 
The other possibility is that State Department mail touched the anthrax-filled letter sent to Daschle and became contaminated. But health officials have said it's unlikely that cross-contamination would involve enough airborne spores to give a mail handler inhalation anthrax. 
Boucher said the department now was planning to examine undelivered mail in Washington and in embassies around the world that passed through the Sterling facility. That mail has been held since Oct. 24, when the mail handler was diagnosed with anthrax. 
It was unclear why the State Department waited for results from environmental testing to begin looking for the letter and why the FBI hasn't been more eager to find it. 
Dr. Cedric Dumont, the State Department's medical director, said his department felt no urgency from the CDC or the FBI to move more quickly, so the department took its time, not testing the mail sorting machines until last week. 
"It just was not the highest priority," he said. 
Dumont said CDC officials were reluctant to conclude that another letter was lurking in the system until the machines were tested. CDC officials, however, downplayed the test results, saying they simply bolster their established theory. 
At the FBI, a spokesman said investigators had not searched through the mail earlier because investigators officials believed that, if there was another letter, it had been delivered already. 
But Dumont said there was no reason to believe that. And Boucher said that if the letter already had been delivered, someone presumably would have opened it and noticed the powder or gotten sick. 
"We have to assume that we stopped it, we stuck it in our system where all the mail is sealed," he said. "We have to presume that we will be able to find whatever it is as we go through the mail in our system."