BOSTON (CBSNewYork/AP) -- Boston Marathon bombing suspect Dzhokhar Tsarnaev was charged by federal prosecutors in his hospital room Monday with conspiring to use a weapon of mass destruction -- a crime that carries a possible death sentence.
Tsarnaev remains in serious condition and virtually unable to speak with a gunshot wound to the throat.
He uttered only one word to a U.S. Magistrate judge Monday afternoon, saying, "No," when asked if he could afford a lawyer, CBS 2's Jessica Schneider reported.
He has been answering other questions with a nod, or pen and paper.
WEB EXTRA: Read The Complaint Against Tsarnaev (.pdf)
"I find that the defendant is alert, mentally competent and lucid," the magistrate judge said, according to a transcript of the proceedings. "He is aware of the nature of the proceedings."
Tsarnaev, 19, told authorities from his hospital bed Monday that he and his brother Tamerlan, 26, acted alone in last week's attack, officials told CBS News.
Officials have said Dzhokhar Tsarnaev and his older brother set off the twin explosions at last week's marathon that killed three people and wounded more than 180. His brother died Friday after a fierce gun battle with police.
"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," said U.S. Attorney General Eric Holder. "Our thoughts and prayers remain with each of the bombing victims and brave law enforcement professionals who lost their lives or suffered serious injuries as a result of this week's senseless violence."
In addition to the weapon of mass destruction charge, Dzhokhar Tsarnaev is charged with one count of malicious destruction of property by means of an explosive device resulting in death, according to the criminal complaint.
"The impact of these crimes has been far-reaching, affecting a worldwide community that is looking for peace and justice. We hope that this prosecution will bring some small measure of comfort both to the public at large and to the victims and their families that justice will be served," said Carmen Ortiz, U.S. Attorney for the District of Massachusetts.
Two U.S. officials said preliminary evidence from an interrogation suggests the suspects were motivated by religion, but were apparently not tied to any Islamic terrorist groups.
The two brothers, from southern Russia, practiced Islam. The U.S. officials spoke Monday on condition of anonymity because they were not authorized to publicly discuss the investigation.
Dzhokhar Tsarnaev, who is a naturalized U.S. citizen, will not be charged as an enemy combatant. The move ended speculation that mounted over the weekend when several Republican lawmakers called for the designation.
Charging Tsarnaev as an enemy combatant would have had a wide range of legal implications. He will instead be tried in federal court.
Tsarnaev also is likely to face state charges in connection with the fatal shooting of MIT police officer Sean Collier in Cambridge, said Stephanie Guyotte, a spokeswoman for the Middlesex District Attorney's Office.
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.
"A few seconds after he finishes the call, the large crowd of people around him can be seen reacting to the first explosion," the complaint said. "Virtually every head turns to the east (towards the finish line) and stares in that directions in apparent bewilderment and alarm. Bomber Two (Dzhokhar Tsarnaev), virtually alone among the individuals in front of the restaurant, appears calm."
The document does not say whether suspect Dzhokhar Tsarnaev is thought to have used the cell phone as a detonator.
The complaint then goes on to say, "He walks away without his knapsack, having left it on the ground where he had been standing. Approximately 10 seconds later, an explosion occurs in the location where Bomber Two had placed his knapsack."
The court papers also detailed the long night of crime Thursday and the subsequent search Friday that led to the older brother's death and the younger one's capture.
After carjacking a man in a Mercedes-Benz, one of the suspects told the victim, "Did you hear about the Boston explosion? I did that. I am serious," the affidavit said.
The complaint states the suspect then, "removed the magazine from his gun and showed the (carjacking) victim that it had a bullet in it, and then reinserted the magazine. The man then stated, 'I am serious.'"
Police eventually found Dzhokhar Tsarnaev hiding in a boat in Watertown on Friday evening after a day-long search that paralyzed the Boston area. Massachusetts state police released an infrared video they said shows him trying to evade capture.
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.
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 the suspected bombers in the surveillance photos the FBI released a few days after the attack.
U.S. officials had said previously that the elite interrogation team would question Dzhokhar Tsarnaev without reading him his Miranda rights -- which guarantee the right to remain silent and the right to an attorney -- something that is allowed on a limited basis when the public may be in immediate danger, such as when bombs are planted and ready to go off.
In a statement, several GOP lawmakers, including Rep. Peter King, R-N.Y. and Sens. John McCain, R-Ariz., Lindsey Graham, R-S.C., and Kelly Ayotte, R-N.H., called the decision not to immediately Mirandize Tsarnaev "sound and in our national security interests."
However, they expressed concern that "exclusively relying on the public safety exception to Miranda could very well be a national security mistake. It could severely limit our ability to gather critical information about future attacks from this suspect."
"Unfortunately the Boston Marathon massacre is a vivid, vivid wakeup call that the enemy is still there, still wants to kill us, and will not rest and we cannot let our guard down," King said Monday.
American Civil Liberties Union Executive Director Anthony Romero has said the legal exception applies only when there is a continued threat to public safety and is "not an open-ended exception" to the Miranda rule.
The federal Public Defender's Office in Massachusetts said it has agreed to represent Tsarnaev. Miriam Conrad, public defender for Massachusetts, said he should have a lawyer appointed as soon as possible because there are "serious issues regarding possible interrogation."
Massachusetts Gov. Deval Patrick said that he has no idea what motivated the suspects. Speaking on CBS' "Face the Nation," Patrick said it's hard to imagine why someone would deliberately harm "innocent men, women and children in the way that these two fellows did."
As the investigation continues, people in Boston and other cities observed a moment of silence for the victims of the bombings one week after the explosions. The two bombs exploded at 2:50 p.m. a week ago Monday.
In Connecticut, Gov. Dan Malloy had directed state agencies to join Massachusetts in the afternoon moment of silence and urged residents to do the same.
"Connecticut stands with Massachusetts in honoring the victims of the tragedy last week in Boston," Malloy said in a statement. "Our thoughts remain with the victims of this senseless tragedy and the families mourning the loss of their loved ones."
Also Monday, 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.
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