WASHINGTON, Oct. 23 (UPI) -- Threatening letters containing white powder have been sent to more than 50 U.S. banks and financial institutions, the FBI said Thursday.

DENVER, Oct. 21 (UPI) -- Chase banks in eight states and the District of Columbia received menacing letters containing white powder this week, federal authorities said Tuesday.

WASHINGTON, May 28 (UPI) -- The FBI has warned 18,000 U.S. law enforcement agencies al-Qaida will issue a new call for use of weapons of mass destruction, ABC News reports.

WASHINGTON, March 27 (UPI) -- The FBI says it has recovered the remains of three more individuals in the ongoing investigation into the kidnapping of five Western contractors in Iraq.

WASHINGTON, March 4 (UPI) -- Ricin has been a byword for terrorism in the mass media since Colin Powell used it to link Iraq-based terrorists to groups plotting attacks in Europe as part of the U.S. case for invasion in 2003. But the ricin in that incident turned out to be no more real than Saddam Hussein's weapons of mass destruction, and experts say that the toxin is so difficult to purify it is unlikely to ever be used successfully in a terror attack.

CHICAGO, Nov. 9 (UPI) -- U.S. and local law enforcement agencies are downplaying "uncorroborated" terrorist threats to malls in Chicago and Los Angeles.

WASHINGTON, Oct. 15 (UPI) -- The U.S. Department of Homeland Security began a preparedness exercise Monday in two states, Guam and the District of Columbia.

WASHINGTON, March 17 (UPI) -- The FBI says U.S. school buses are safe despite a federal bulletin indicating individuals with ties to extremist groups have obtained buses and licenses.