"Did you hear about the Boston explosion? I did that."
BOSTON (AP) -- Boston Marathon bombing suspect Dzhokhar Tsarnaev was charged by federal prosecutors in his hospital room Monday with using a weapon of mass destruction to kill -- a crime that carries a possible death sentence.
Officials have said Tsarnaev, 19, and his older brother set off the two pressure-cooker bombs at last week's race that sprayed shrapnel into the crowds, killing three people and wounding more than 180. His brother, Tamerlan, 26, died Friday after a fierce gunbattle with police.
Tsarnaev was listed in serious but stable condition at Beth Israel Deaconess Medical Center, unable to speak because of a gunshot wound to the throat.
In a criminal complaint outlining the evidence, the FBI said Tsarnaev was seen on surveillance cameras putting a knapsack on the ground near the site of the second blast and then manipulating a cellphone and lifting it to his ear.
After the first explosion ripped through the crowd, a calm-looking Tsarnaev quickly walked away, and about 10 seconds later, the second blast occurred where he left the knapsack, the FBI said.
The FBI did not make it clear whether authorities believe he used his cellphone to detonate one or both of the bombs or whether he was talking to someone.
The court papers also said that during the long night of crime Thursday and Friday that led to the older brother's death and the younger one's capture, one of them told a carjacking victim: "Did you hear about the Boston explosion? I did that."
Tsarnaev was charged with using and conspiring to use a weapon of mass destruction against persons and property, resulting in death. He is also likely to face state charges in connection with the shooting death of an MIT police officer.
The Obama administration said it had no choice but to prosecute Tsarnaev in the federal court system. Some politicians had suggested he be tried as an enemy combatant in front of a military tribunal, where he would be denied some of the usual U.S. constitutional protections.
But Tsarnaev, an ethnic Chechen from Russia who has lived in the United States for about a decade, is a naturalized U.S. citizen, and under U.S. law, American citizens cannot be tried by military tribunals, White House spokesman Jay Carney said.
Carney said that since the Sept. 11 attacks, the federal court system has been used to convict and incarcerate hundreds of terrorists.
In its criminal complaint, the FBI said it searched Tsarnaev's dorm room at the University of Massachusetts-Dartmouth on Sunday and found BBs as well as a white hat and dark jacket that look like those worn by one of one of the suspected bombers in the surveillance photos the FBI released a few days after the attack.
Seven days after the bombings, meanwhile, Boston was bustling Monday, with runners hitting the pavement, children walking to school and enough cars clogging the streets to make the morning commute feel almost back to normal.
Residents to observe a moment of silence at 2:50 p.m., the time the first of the two bombs exploded near the finish line. Bells were expected to toll across the city and state after the minute-long tribute to the victims.
Also, hundreds of family and friends packed a church in Medford for the funeral of bombing victim Krystle Campbell, a 29-year-old restaurant worker. A memorial service was scheduled for Monday night at Boston University for 23-year-old Lu Lingzi, a graduate student from China.
Fifty-one victims remained hospitalized Monday, three of them in critical condition.
At the Snowden International School on Newbury Street, a high school set just a block from the bombing site, jittery parents dropped off children as teachers -- some of whom had run in the race -- greeted each other with hugs.
Carlotta Martin of Boston said that leaving her kids at school has been the hardest part of getting back to normal.
"We're right in the middle of things," Martin said outside the school as her children, 17-year-old twins and a 15-year-old, walked in, glancing at the police barricades a few yards from the school's front door.
"I'm nervous. Hopefully, this stuff is over," she continued. "I told my daughter to text me so I know everything's OK."
Tsarnaev was captured Friday night after an intense all-day manhunt that brought the Boston area to a near-standstill. He was cornered and seized, wounded and bloody, after he was discovered hiding in a tarp-covered boat in a Watertown backyard.
He had apparent gunshot wounds to the head, neck, legs and hand, the FBI said in court papers.
Sen. Dan Coats of Indiana, a member of the Senate Intelligence Committee, said Sunday that Tsarnaev's throat wound raised questions about when he will be able to talk again, if ever. It was not clear whether the wound was inflicted by police or was self-inflicted.
The wound "doesn't mean he can't communicate, but right now I think he's in a condition where we can't get any information from him at all," Coats told ABC's "This Week."