Prosecutors formally charged Dzhokhar Tsarnaev with the bombings at the Boston Marathon in a hearing held on Monday in his hospital room, accusing him of crimes that carry the possibility of the death penalty.
The 19-year-old ethnic Chechen can be seen in video taken by security cameras placing a backpack near the finish line of the world-renowned race last Monday, the criminal complaint said, alleging he acted in concert with his older brother, who was killed during a shootout with police early Friday.
The brothers carried two backpacks containing pressure cooker bombs that ripped through the crowd near the finish line, killing three people and wounding more than 200, the complaint said. Ten people lost limbs from the bombs packed with nails and ball bearings.
Dzhokhar Tsarnaev told investigators in his hospital room that he and his brother acted alone, without any help, according to reports by CNN and the New York Times. He said his older brother was the driving force behind the bombings, CNN reported. The Times said Dzhokhar Tsarnaev admitted to investigators to being involved in planting the bombs. These reports could not be independently confirmed.
Dzhokhar Tsarnaev was captured late Friday after a massive manhunt. He was hospitalized with what the criminal complaint said were gunshot wounds to his head, neck, legs and hand.
The charges came one week after the bombings, as Boston slowly returned to normal, but a fresh security scare arose as Canadian police said they had thwarted an "al Qaeda-supported" plot to derail a passenger train.
U.S. officials said the attack would have targeted a rail line between New York and Toronto, although Canadian police said only that the plot involved a train route in the Toronto area.
Tsarnaev was charged with using a weapon of mass destruction and with malicious destruction of property resulting in death. Each count carries the possibility of the death penalty if he is convicted.
More charges are likely, legal experts said.
The 10-page complaint drew from video and still images captured by security cameras, the media and the public at the race before and after the bombing. It did not mention a motive, leaving that as one of the mysteries of the investigation.
According to a transcript of the bedside legal proceeding, the teenager, mostly unable to speak due to his injuries, nodded when questioned by federal Magistrate Judge Marianne Bowler, who asked him if he could answer questions and could follow what was happening. The judge also read him his constitutional rights.
Asked by the magistrate if he could afford a lawyer, Tsarnaev said "No." Three public defenders, appointed by the court, were in the room. They did not respond to requests seeking comment afterward.
A sworn FBI statement in support of the criminal complaint revealed the recollection of a man whose car was allegedly hijacked by the brothers while they tried to escape on Thursday night.
"Did you hear about the Boston explosion?" one of the brothers is said to have told the carjack victim. "I did that."
On Monday, Boston-area hospitals were still treating at least 48 people, with at least two listed in critical condition.
The complaint said that 30 seconds before the first explosion, Dzhokhar Tsarnaev started fidgeting with his cellphone. After the blast, virtually everyone around him turned toward the blast "in apparent bewilderment and alarm," while he appeared calm, it said.
He then left his backpack on the ground and walked away, the complaint said. About 10 seconds later the second explosion ripped through the crowd.
At 2:50 p.m. (1850 GMT) on Monday, the city paused to mark the moment a week earlier when the bombs exploded. A funeral was held for Krystle Campbell, a 29-year-old restaurant manager who was killed in the bombings, as was a memorial service for another victim, Chinese graduate student Lingzi Lu, 23.
An 8-year-old boy, Martin Richard, was also killed.
Police on Monday searched a parking area in Cambridge, Massachusetts, where an owner of an auto service business across the street said the Tsarnaevs' father used to work on cars.
Officials did not say what police were looking for.
Near the site of the bombings, Kevin Brown, a 59-year-old carpenter minding one of the many makeshift memorials to the victims, said he hoped Tsarnaev would be convicted and face the death penalty.
"His bomb was the second one which killed that little boy," he said. "He doesn't deserve to live."
Tsarnaev's capture capped a tense 26 hours after the FBI released the first pictures of the two bombing suspects, still unidentified, on Thursday.
Five hours after their faces appeared on TV screens and websites around the world, the brothers shot and killed a university policeman, carjacked a Mercedes and sought to evade police by hurling bombs during a shootout in a Boston suburb, police said.
Tamerlan Tsarnaev, 26, was shot in an exchange of gunfire with police and run over by his younger brother, police said. Dzhokhar Tsarnaev later abandoned the car and fled on foot, evading police for nearly 20 more hours until he was found hiding and bleeding in a boat.
"Although our investigation is ongoing, today's charges bring a successful end to a tragic week for the city of Boston, and for our country," U.S. Attorney General Eric Holder said in a statement.
In choosing the civilian justice system, U.S. authorities opted against treating Tsarnaev, a naturalized U.S. citizen, as an enemy combatant.
Tamerlan Tsarnaev, a legal U.S. resident, visited relatives in the volatile region of Chechnya for two days during his six-month trip out of the United States last year, his mother, Zubeidat Tsarnaeva and aunt, Patimat Suleimanova, told Reuters in Dagestan on Monday.
U.S. authorities were investigating whether he became radicalized and if he was involved with or was influenced by Chechen separatists or Islamist extremists there.
That trip, combined with Russian interest in Tamerlan Tsarnaev communicated to U.S. authorities and an FBI interview of him in 2011, have raised questions whether danger signals were missed.
U.S. lawmakers planned to question senior security officials this week about whether the FBI mishandled information on the elder brother, who was flagged by Russia as a possible Islamist radical.
The Tsarnaev brothers emigrated to the United States a decade ago from Dagestan, a predominantly Muslim region in Russia's Caucasus. Their parents, who moved back to southern Russia some time ago, have said their sons were framed.
The elder brother twice disrupted sermons to challenge views expressed by preachers leading services at a Cambridge mosque, the Islamic Society of Boston said on Monday.
But neither brother "expressed any hint of violent sentiments or behavior," the group said in a statement. "If they had, the FBI would have immediately been called."
Neither was a member or regular attendee of the Cambridge mosque, it said.
Tamerlan Tsarnaev was married, and a crowd of reporters and photographers gathered on Monday outside the home of his wife in North Kingston, Rhode Island. Several family members came and went without making any comment.
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