Letters containing a suspicious powdery substance have been arriving in several Congressional offices, and one arrived on Thursday at Sen. Joe Lieberman’s office at 1 Constitution Plaza in Hartford.
Lieberman’s office received a warning on Wednesday to look out of packages and contacted authorities when one matching the description arrived on Thursday, Lieberman's staff said.
They did not open the package and authorities tested the substance and determined it it not harmful.
The Associated Press reports that the letters bear a return address from "The MIB" and the Portland, Oregon return address on the letters appears to be phony.
The powder inside has proved to be harmless, the FBI and the Senate's top law enforcement officer told the AP.
The senator was in the state, but was not at the office at the time, according to his staff.