Delta Flight 253

"There is no doubt that he was in contact with al Qaeda in Shabwa province," Rashad al Alimi, Yemen's deputy prime minister said in 2010. "Maybe with Anwar al-Awlaki."

Abdulmutallab worked largely independently after his training and indoctrination in Yemen, planning to down a commercial airliner over a large U.S. city.

He later told investigators al-Awlaki directed him to carry out the attack on an airliner.

Credit: CBS/AP