A hazardous materials team cleans a blast site near the Boston Marathon… (Kevork Djansezian / Getty…)
BOSTON — In an extraordinary proceeding in a hospital room Monday, federal authorities charged Dzhokhar Tsarnaev with using a weapon of mass destruction in the bombings that killed three people and injured more than 200 others at last week's Boston Marathon.
Appearing at the bedside of the grievously wounded 19-year-old, a federal magistrate read the criminal charges against him and advised him of his legal rights. If convicted, Tsarnaev, a Russian immigrant who became a U.S. citizen last year, could face the death penalty.
"So you have your lawyers here," U.S. Magistrate Marianne B. Bowler said to Tsarnaev after a trauma surgeon determined that he was feeling well enough to answer questions. Tsarnaev, whose injuries have limited his ability to speak, nodded yes.
The magistrate told him he did not have to speak or to cooperate with the government. A prosecutor and an assistant federal defender representing Tsarnaev — who said he had spoken "very briefly" to his client — stood by.
"Do you understand everything I have said about your right to remain silent?" Bowler asked.
Once again, Tsarnaev nodded.
Tsarnaev, who was not asked how he intended to plead to the charges, spoke just once — when Bowler asked whether he could afford an attorney.
"No," he replied, according to an official transcript.
"I find that the defendant is alert, mentally competent and lucid," Bowler said before setting the next hearing for late May.
Before Tsarnaev was formally charged, two sources familiar with the investigation said officials were able to ask him several questions, and that although he could barely speak, he was cooperative. One official with knowledge of the investigation said Tsarnaev acknowledged that he and his brother were motivated by jihadist ideology.
Authorities are still investigating whether the two men had ties to any radical Islamic groups.
The criminal complaint released Monday was accompanied by an affidavit in which the FBI sketched out details of its case against Tsarnaev, including a chilling outline of his movements along the marathon route and his calm demeanor as the first bomb went off.
The affidavit, and the dramatic developments inside Beth Israel Deaconess Medical Center, came one week to the day from the attack. At precisely 2:50 p.m., the moment one week ago when the first bomb exploded, bells tolled throughout the city.
As American flags fluttered above them, mourners gathered at the makeshift memorial near the Boylston Street finish line, bowing their heads in prayer. People around the world, including President Obama, traders on the floor of the New York Stock Exchange and runners at a race in Paris, joined them in a moment of silence.
"God bless the people of Massachusetts," Gov. Deval Patrick said after several minutes on the steps of the state Capitol. "Boston strong."
As investigators tried to unravel the possible motives of the bombing suspects and trace their recent activities, the search for clues fanned out well beyond Boston.
Authorities searched an apartment in nearby New Bedford belonging to two people believed to have ties to the Tsarnaevs, and were also examining whether the second bombing suspect, Tsarnaev's 26-year-old brother Tamerlan, had any connection to an unsolved triple homicide in Waltham, Mass., in 2011. (The elder Tsarnaev died Friday after a firefight with police in the Boston suburb of Watertown.)
The affidavit released Monday tracked the bombers' actions during four violent days.
At 2:38 p.m. on marathon day, a security camera near the corner of Boylston and Gloucester Streets captured two young men, whom officials believe to be the Tsarnaev brothers, turning onto Boylston Street and walking toward the finish line, each carrying a large knapsack.
Video footage from a series of security cameras showed the two standing together for a moment and then parting ways, FBI Special Agent Daniel Genck said in the affidavit.
At 2:45 p.m., the one believed to be Dzhokhar Tsarnaev stopped in front of the Forum restaurant — close to the site of the second blast — for four minutes, looking at his cellphone and at one point appearing to take a picture with it.
About 30 seconds before the first explosion, which took place a short distance down Boylston Street, the younger Tsarnaev lifted his phone to his ear as if speaking on it for about 18 seconds, the affidavit said.
"A few seconds after he finishes the call, the large crowd of people around him can be seen reacting to the first explosion," wrote Genck, who is assigned to a counter-terrorism squad in the FBI's Boston field office. "Virtually every head turns to the east (towards the finish line) and stares in that direction in apparent bewilderment and alarm."