Congressional offices receive mailed threats

WASHINGTON (AP) -- Some congressional offices have received threatening letters containing a "suspicious powdery substance," the Senate's top law enforcement officer said Wednesday.

Sergeant-at-Arms Terrance Gainer said in a memo to Senate offices that the letters were sent to three state and home district offices and that the substance was tested and found to be harmless.

Letters were also sent to several media organizations. FBI spokesman Peter Donald said agents had responded to Viacom and at least one other location in New York. Preliminary tests showed that the powder did not pose a threat, he said.

The letters tell the recipients that there is a "10 percent change you have just been exposed to a lethal pathogen."

Gainer said the author of the letters said that additional letters would be sent and that some of these could contain actual harmful material.

Gainer said Capitol authorities were working closely with federal and local law enforcement in the investigation.

The letters bore a return address from "The MIB" and were postmarked Portland, Ore.

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