Federal authorities on Monday charged Dzhokhar Tsarnaev with one count of conspiring to use a weapon of mass destruction against persons and property in the United States in connection with last week's bombing of the Boston Marathon.

The 19-year-old, who was captured Friday night after an exhaustive search and two bloody firefights, was also charged with one count of using an improvised explosive device and one count of attempting "malicious destruction of property." 

If convicted of the charges, he could face the death penalty or life in prison.

The White House announced Monday it would not hold Tsarnaev as an enemy combatant. He is being questioned at a Boston hospital, where authorities say he is in serious condition. 

Tsarnaev is being charged in a terrorist attack that killed three people and wounded more than 200, according to the affidavit. His older brother Tamerlan was killed Friday morning after a high-speech chase through Cambridge and Watertown, Mass. 

The two brothers allegedly carjacked a Mercedes SUV, with one of them telling the driver: "Did you hear about the Boston explosion? I did that."

The man removed the magazine from his gun and showed the victim that it had a bullet in it and then re-inserted the magazine. The man then stated, "I am serious."

The car then picked up a second man, according to the affidavit, which does not specify which man was believed to be Dzhokhar Tsarnaev and which was believed to be Tamerlan Tsarnaev.

The affidavit does not include any charges related to the killing of Massachusetts Institute of Technology police officer Sean Collier.

The affidavit also includes evidence putting Dzhokhar Tsarnaev at the bombing — and reacting differently than others. 

Seconds before the bombing, he was on his cell phone, it states. When the blast went off, he calmly glanced toward the explosion then quickly but calmly walked in the other direction. 

"Approximately 30 seconds before the first explosion, he lifts his phone to his ear as if he is speaking on his cell phone, and keeps it there for approximately 18 seconds," the affidavit states. "A few seconds after he finished the call, the large crowd of people around him can be seen reacting to the explosion. Virtually every head turns to the east (towards the finish line) and stares in that direction in apparent bewilderment and alarm. 

"Bomber Two, virtually alone among individuals in front of the restaurant, appears calm," it continues. "He glances to the east and then calmly but rapidly begins moving to the west, away from the direction of the finish line."

Police searched Dzhokhar Tsarnaev's dorm room at the University of Massachusetts Dartmouth and found "a large pyrotechnic, a black jacket and a white hat" consistent with what they believe he was wearing at the site of the bombing, the affidavit states.

This story was posted at 1:47 p.m. and updated at 3:00 p.m.