He was born and raised in the United States, and killed by the United States. And now from beyond the grave he inspires a new generation of would-be terrorists to attack the United States.
Militant cleric Anwar al-Awlaki continues to speak through sermons posted online, and U.S. officials are investigating whether his words may have influenced Boston bombers Tamerlan and Dzhokhar Tsarnaev.
A U.S. government official told CNN's Jake Tapper on Tuesday that "the preachings of Anwar al-Awlaki were likely to have been among the videos they watched." A U.S. government source had previously told CNN that Dzhokhar Tsarnaev had claimed the brothers had no connection to overseas Islamist terrorist groups and were radicalized through the Internet.
Al-Awlaki lived in Colorado, California and Virginia before leaving the United States in 2002. At one point he met two of the men who would be among the 9/11 hijackers, an encounter later investigated by the FBI. There is no evidence that al-Awlaki knew of their plans.
From about 2006 onward he became increasingly influential among would-be jihadists around the world with his eloquent online sermons delivered in fluent and colloquial English. Al-Awlaki was killed in a U.S. drone strike in a remote part of Yemen in September 2011, along with another American, Samir Khan.
U.S investigators are examining whether the Tsarnaev brothers downloaded or viewed a bomb formula that appeared in Inspire, the online English-language magazine published by al Qaeda in the Arabian Peninsula. Al-Awlaki is believed to have been the driving force behind that magazine and Samir Khan was its editor.
The pressure cooker devices exploded in Boston had several striking similarities to a design in the first issue of the magazine in the summer of 2010 "How to build a bomb in Your Mom's Kitchen."
The magazine instructed would-be jihadists in the West to deploy multiple devices and set them off simultaneously in a crowded space. Another issue of the magazine published a year ago called for attacks at crowded sports venues.
The Inspire recipe "How to Build a Bomb in your Mom's Kitchen" has been linked to multiple Islamist terrorist plots on both sides of the Atlantic. It was downloaded by a group of Islamist extremists plotting to bomb London in late 2010.
In July 2011, an American Muslim soldier from Fort Hood, Texas -- Naser Jason Abdo -- downloaded the recipe and bought pressure cookers and shotgun shells from which he could extract explosive powder. Abdo was arrested before he had assembled a bomb and was sentenced last year to two consecutive life prison sentences for attempted use of a weapon of mass destruction.