WASHINGTON (AP) -- The Senate's top law enforcement officer says congressional offices have received threatening letters containing a suspicious powdery substance.
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.
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 were postmarked Portland, Ore.