The FBI suspected that US-born Al-Qaeda cleric Anwar al-Awlaqi, killed in a 2011 drone strike in Yemen, could have bought air tickets for three of the 9/11 hijackers before the attacks.
The FBI is appealing for information about the travels of a suspected serial killer believed to have murdered up to 15 people over more than a decade, after his suicide in jail last weekend.
President Barack Obama backed the commander of US forces in Afghanistan on Tuesday after the top general was dragged into the sex scandal that brought down CIA director David Petraeus.
FBI agents searched the home of the woman at the center of a sex scandal behind David Petraeus's decision to step down as head of the Central Intelligence Agency.
The FBI uncovered the affair that led to the resignation of CIA chief David Petraeus while investigating threatening emails sent by his lover to a second woman.
The FBI has investigated an incident that saw at least one Republican congressman swim naked at a drinking party in Israel last year attended by top leadership staff, Politico reported Sunday.
Bulgarian police, the FBI and Interpol are struggling to identify a suicide bomber who killed six people, including five Israelis, as the US said the attack bore the "hallmarks" of Hezbollah.
FBI agents have recovered what is believed to be a Matisse painting valued at $3 million that was stolen from a Venezuelan museum 10 years ago, and arrested two suspects.