Updated

A Nigerian who pleaded guilty to trying to blow up a Detroit-bound plane began his path to terrorism with a text message from a top Al Qaeda figure in Yemen, the U.S. government said Friday in a court filing that discloses new details about their relationship.

Umar Farouk Abdulmutallab faces life in prison at his sentencing next Thursday. Although the punishment is mandatory, prosecutors filed a memo urging the judge to also order the maximum penalty for seven other crimes, which range from 20 years to life in prison.

Abdulmutallab is an "unrepentant would-be mass murderer who views his crimes as divinely inspired and blessed, and who views himself as under a continuing obligation to carry out such crimes," the U.S. attorney's office said.

In October, on the second day of trial, Abdulmutallab pleaded guilty to trying to bring down a Christmas 2009 Amsterdam-to-Detroit flight with a bomb in his underwear. The bomb, however, didn't go off. He called it a "blessed weapon" in retaliation for the poor treatment of Muslims worldwide.

It has been known that Abdulmutallab traveled in 2009 to Yemen to volunteer for terrorism and find Anwar al-Awlaki, an American-born cleric and one of the best-known Al Qaeda figures.

But the government's court filing offers more details, based on Abdulmutallab's interviews with the FBI in 2010.

"Once in Yemen, defendant visited mosques and asked people he met if they knew how he could meet al-Awlaki," the government said.

Finally, after providing his cell phone number to someone, Abdulmutallab got a text message from al-Awlaki, who agreed to talk to him, prosecutors said.

"It was agreed that defendant would send al-Awlaki a written message explaining why he wanted to become involved in jihad. ... After receiving defendant's message, al-Awlaki sent defendant a response, telling him that al-Awlaki would find a way for defendant to become involved in jihad," the government said.

After a three-day stay at al-Awlaki's house, Abdulmutallab was accepted for a "martyrdom mission," the government said.

"Al-Awlaki instructed defendant that the only requirements were that the attack be on a U.S. airliner, and that the attack take place over U.S. soil. Beyond that, al-Awlaki gave defendant discretion to choose the flight and date," the government said.

Abdulmutallab is acting as his own lawyer. A message seeking comment was left Friday with an attorney who is assisting him.

Al-Awlaki and the bomb maker were killed by U.S. drone strikes in Yemen last year, just days before Abdulmutallab's trial.