The letter has been turned over to the FBI's Joint Terrorism Task Force for testing and investigation.

WSJ: Secret Service: Letter to White House intercepted

The Secret Service said the letter to Obama was intercepted by a White House mail screening facility, and it was turned over to the FBI's Joint Terrorism Task Force for testing and investigation.

WSJ: Union: NY mayor threats postmarked Shreveport, La.

Listen to University of North Carolina testing expert Gregory Cizek, who participated in the state investigation of cheating in Atlanta.

CNN: STORY HIGHLIGHTS

Sumwalt said the NTSB investigation to determine a likely cause will include routine testing of railroad employees for drugs and alcohol, testing of the track and rail signals and examinationof the video footage from the front of the train.

WSJ: Mo. highway buckles after rail cars hit overpass

Bonds' testimony in December 2003 was part of the investigation that targeted his personal trainer, Greg Anderson, and employees of the California drug testing laboratory known as the Bay Area Laboratory Co-operative, or BALCO.

CNN: STORY HIGHLIGHTS

Empirical investigation as posited by Morphological Analysis and more generally by others is currently the most effective means of testing complex or wicked problems such as cyber security.

FORBES: Written by David Lowenstein and Risu Na