FBI tests Leahy anthrax letter

The Leahy letter, top, is similar to the Daschle letter.

WASHINGTON (CNN) -- Hoping to find new clues to origins of at least three anthrax-tainted letters sent through the nation's mail system, investigators planned Saturday to study -- in a controlled environment -- a letter they said was similar to others addressed to a U.S. senator and two national media outlets.

Investigators at Fort Detrick, Maryland, said they will proceed carefully to preserve evidence that may be found in the envelope, addressed to Sen. Patrick Leahy, D-Vermont.

Evidence in similar letters addressed to Senate Majority Leader Tom Daschle, NBC News anchor Tom Brokaw and The New York Post was destroyed when the letters were opened and anthrax spores escaped into the air.

"I'm hoping that the one bright light in all of this might be that this letter will give us further evidence to find out who is doing this," Leahy said at a Saturday news conference. "You're looking for a needle in a haystack, but we've found those needles before."

The U.S. government is offering a $1,250,000 reward for information leading to the arrest of the mailer of anthrax-laced letters, said Van Harp, assistant director of the FBI's Washington office .

"We are asking for the public's help. This is going to be solved in one of three ways: good police work ... a tip, or the scientific or medical community, who are working closely with law enforcement," said Harp.

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"This is a cold-blooded murderer," he said. "There are four individuals dead as a result of this, none of them the intended targets."

The Leahy letter was found Friday by hazardous materials experts wearing environmental protection suits, sorting through 280 barrels of mail addressed to Capitol Hill. Those barrels have been quarantined at a facility in Virginia since the discovery of an anthrax-laden letter sent to Daschle, which one of his staffers on October 15 in the Hart Senate Office Building.

Investigators have gone through all 280 barrels of congressional mail held in a facility in Virginia, but cannot be certain no other letters like the one to Daschle and Leahy exist, an FBI official said. The reason: Some mail bound for lawmakers is part of the batch of mail sent from the Brentwood postal facility in Washington to be sanitized in Ohio.

Field tests on the barrel that held the letter to Leahy came up positive for anthrax spores, which prompted investigators to search its contents, one letter at a time.

From New Jersey

A senior congressional aide said Friday the letter's handwriting caught investigators' attention, and it was sent through sensor machines, which can detect the presence of biological agents. The letter "sent the meters off the charts," the aide said.

The FBI on Saturday made public a copy of the envelope addressed to Leahy. The handwriting was close to that on the Daschle and Brokaw letters, and the return address on the letter was to an elementary school in New Jersey -- just like on the envelope to Daschle.

The letter addressed to Leahy was postmarked from Trenton, New Jersey, on October 9 -- the same day the Daschle letter was mailed from that city. The Brokaw letter was postmarked from Trenton on September 18.

The FBI said the results of the first round of testing on the Leahy letter came back "presumptive positive" for anthrax.

Leahy said FBI Director Robert Mueller informed him immediately about the discovery, noting that his staffers said they felt fine. The Centers for Disease Control and Prevention and an attending physician said Leahy's staff needed no further testing.

Leahy's office is in the Russell Senate Office Building, which was closed after the Daschle letter was found. The building was reopened when spot checks for anthrax turned up negative. The Hart building remains closed for decontamination after several anthrax "hot spots" were found there.

The Russell and the Dirksen Senate Office Buildings would be closed Saturday afternoon for further testing prompted by the discovery of the Leahy letter, Capitol Police said.