Canadian authorities are also running down leads of any Canadian citizens who have traveled to Yemen, a senior official there said.
Awlaki, an American citizen who lives in Yemen, has been connected by authorities to the accused Northwest bomber, the accused shooter at Fort Hood and several other men convicted of terrorist activity in the United States and Canada.
As part of the additional scrutiny, federal agents are conducting extensive background checks on every passenger who flew to Detroit on the Northwest flight in case one of them might have been sent as a "spotter" on the mission.
Federal agents also tell ABCNews.com they are attempting to identify a man who passengers said helped Abdulmutallab change planes for Detroit when he landed in Amsterdam from Lagos, Nigeria.
Authorities had initially discounted the passenger accounts, but the agents say there is a growing belief the man have played a role to make sure Abdulmutallab "did not get cold feet."