FBI focuses on N.J. mail center

Postal Service police patrol the front of the Hamilton Township processing center.

TRENTON, New Jersey (CNN) -- Investigators hunting the source of three anthrax-laced letters addressed to two journalists and a U.S. senator are focusing on the place they were postmarked instead of a local mail route, the FBI said Wednesday.

Meanwhile, officials said Wednesday the letters to Senate Majority Leader Tom Daschle, NBC anchor Tom Brokaw and the editor of the New York Post are believed to have passed through another New Jersey mail facility.

The Carteret Hub and Spoke facility in Carteret, New Jersey, where all 104 workers are taking antibiotics to treat anthrax, handles New Jersey mail that goes to New York and Washington, D.C.

Postal Service spokeswoman Diane Todd said the Centers for Disease Control and Prevention was conducting environmental sweeps of the building, but she would not say whether anthrax had been found.

FBI spokeswoman Sandra Carroll said investigators suspect a female mail carrier who worked out of the West Trenton post office in Ewing Township may have contracted cutaneous (skin) anthrax from a letter picked up at the Trenton Distribution and Processing Center in Hamilton Township.

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She is one of two postal employees in New Jersey with skin anthrax. A third has a suspected case of skin anthrax and a fourth has a suspected case of the more serious inhalation anthrax.

"We're still waiting for some additional information," Carroll said. "We're focusing in the direction of the processing facility," as the location where the female carrier might have contracted the disease.

The postal service is urging bulk mail customers and workers at the West Trenton post office or the Hamilton Township processing center to begin a 10-day course of antibiotics immediately.

Vito Cetta, postal service district manager for central New Jersey, said Tuesday night that 32 of 80 environmental samples from the Hamilton Township facility tested positive for anthrax. All 19 tests at the West Trenton post office were negative.

Business mailers and postal employees who entered work areas in the facilities between September 18 and October 19 should report to a doctor or hospital for antibiotic treatment, Cetta said.

Regular postal customers are not being urged to seek treatment because no anthrax was found in public areas of either facility, he said.

The letters to Brokaw and the Post were postmarked September18; the letter to Daschle was postmarked October 8.

Carroll said investigators were awaiting the results of tests taken on three large blue collection boxes along the carrier's route, one of which was in front of the Trenton post office.

Test results for contamination are also pending on her mailbag and the truck she drove.

-- CNN correspondents Eileen O'Connor and Susan Candiotti contributed to this report.