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Tracing Tainted Letters Is Daunting Detective Work
Postal inspectors hunting for the senders of anthrax-laden mail have a number of tools to figure out when and where a letter was mailed. But their techniques may be insufficient to find the individuals who sent the envelopes that have generated anxiety among the public and postal workers, according to current and former postal authorities.
Unless there is a major break--such as figuring out where the anthrax was produced or lifting a matching fingerprint from an envelope--the odds are long that law enforcement investigators will track down the culprits.
"I would say if you sent a letter, you will have a reasonable expectation that you will not get caught," said a former top Postal Inspection Service security administrator. "It's just too hard to track them down."
Working closely with the FBI, postal investigators Monday were trying to lift fingerprints from the letters, including one sent to the office of the Senate majority leader, Tom Daschle (D-S.D.), and to take DNA samples from any saliva found on the envelopes.
Meanwhile, the Postal Service announced Monday that it will furnish gloves and filtering face masks to employees who request them. The agency also announced the formation of a special task force of management, union and major corporate mailers to discuss the threat of biological and chemical materials sent through the mail.
Postmaster General Jack Potter urged Americans to combine vigilance with calm. "We have mobilized our military, but we also must mobilize our common sense," he said. "Panic must not defeat us." He told his agency's workers: "If you see a suspicious package or letter, leave it alone. Don't shake it or bump it. Isolate it, and call for help."
Postal inspectors have had success catching those who send bombs through the mail, but few arrests have been made in incidents in which someone sends a threatening letter, whether the letter actually contained hazardous materials or simply claimed to have dangerous contents, officials acknowledged Monday.
After the Unabomber case, in which explosive devices were sent through the mail, the Postal Service changed its rules, banning any packages weighing more than 16 ounces from being dropped into mailboxes. In such cases, they are returned to the sender or examined by postal authorities. Packages heavier than a pound must be handed directly to a clerk at a post office, who can look for anything suspicious and demand to see the mailer's identification.
But there have been no new special security rules for the vast bulk of the mail flow--the envelopes containing bills, letters and greeting cards. The intricate system--which moves 608 million pieces of mail each day--relies on machines to read virtually all addresses and ZIP codes--even hand-scrawled envelopes--and relatively few workers touch an envelope during the sorting process unless it becomes jammed in a machine.
However, employees handle the mail before and after the machines sort it and read the ZIP codes. They unload volumes of mail picked up at boxes, load the trays feeding the sorting machines and prepare the mail for distribution by carriers, who drive and walk the routes to hand-deliver the mail at homes and businesses.
In investigating the anthrax reports in three states and on Capitol Hill, authorities did handwriting analysis on the letters and scrutinized the envelopes to see if they bore any special characteristics that would help determine where they were sold and who bought them, postal and FBI officials said. Authorities are also trying to determine if the packages containing anthrax are from the same source.
And they spent the day trying to "back trace" the mail to see where it came from, and when.
In some cases, it may be possible to tell which particular mail drop was used. Authorities also will be able to determine when a letter was dropped off within a few hours, since U.S. postmarks bear an "a.m." or "p.m." stamp. That "window" can further be identified based on the time of day that mail is picked up in that jurisdiction, the particular routes taken by mail carriers and when the letter was received at a central processing center, according to Bill Hall, acting inspector in charge of the Southern California division of the Postal Service inspectors unit.
In rare cases, it may be possible to get video footage of the sender, since some mail drops are situated near businesses that operate video cameras, such as gas stations and banks.
But they also cautioned that the odds are great that they will not be able to back trace the anthrax-ridden mail to its original senders, especially if the senders took steps to cover their tracks.
"The chances of figuring out where they came from are slim and none," said the former Postal Service investigator.
In the past, many threatening letters turned out to be hoaxes. During 1999 and 2000, there were 178 letters mailed in the United States with threats that they contained anthrax, Hall said. But none of the letters actually contained anthrax, "so we didn't back trace" many of the letters, Hall said. There were 60 threatening letters before the Sept. 11 terrorist attack, none of them legitimate.
In its announcement Monday, the Postal Service sought to reassure its anxious workers, promising the gloves and masks on request, and offering nitrile gloves to those who might be allergic to conventional latex ones. Some workers concerned with the possible health threats from dust in mail processing plants or from the solvents used in inks already had been using masks or gloves.
The Postal Service has promised its unions a nationwide video conference today "giving better and hopefully more specific management instructions and guidance on this issue," said Tom Fahey, a spokesman with the American Postal Workers Union, which represents 366,000 employees.
The former postal investigator said that postal carriers have become terrified of handling the mail despite assurances that anthrax is usually spread only when a letter is opened. The drumbeat of news about more and more anthrax-laden letters is causing waves of near-panic at post offices around the nation, he said.
"Postal inspectors are getting calls from mail rooms all over the place, asking, 'What do we do? They want to know how to identify it,' " said the former administrator, who remains as a consultant to the Postal Service.