The Boston bombing suspect captured by authorities Friday night remained hospitalized in serious condition Saturday, protected by heavily armed guards while the city and its surrounding suburbs, locked down for nearly 24 hours during an intense manhunt, came back to life.
Investigators, meanwhile, were waiting to question the 19-year old suspect, Dzhokar Tsarnaev, to determine a motive and address the lingering questions about Monday's marathon bombings that killed three people and wounded 176 others.
President Obama touched on some of those questions in a Friday night press conference held a short while after police captured Tsarnaev, who had been injured and holed up in a boat parked on the side of a Watertown house, according to authorities. His older brother and alleged accomplice, Tamarlan, was killed with a bomb strapped to his chest after a wild police chase overnight on Thursday.
“Why did young men who grew up and studied here, as part of our communities and our country, resort to such violence,” Obama asked. “How did they plan and carry out these attacks? And did they receive help? The families of those killed deserve answers. The wounded deserve answers."
U.S. Attorney Carmen Ortiz said Friday night that formal charges would be filed in the coming days.
The FBI confirmed it investigated Tamerlan in 2011 for possible extremist ties after receiving information from abroad that he was a "follower of radical Islam" and planned to join an underground group, NBC News reported. Agents questioned him and neighbors and did not find "any terrorism activity, domestic or foreign."
After being apprehended by police Friday night, Dzhokhar Tsarnaev was taken by ambulance to Beth Israel Deaconess Medical Center in Boston where he is receiving treatment. He is believed to have suffered a gunshot wound and lost a lot of blood, police said, and unable to answer questions.
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U.S. officials said when Tsarnaev was well enough to face interrogation, a special team for high-value suspects would question him without reading him his Miranda rights, invoking a rare “public safety exception” triggered by the need to protect police and the public from immediate danger.
An Obama administration official told NBC News that under the present circumstances, the government finds it urgent to determine if the brothers planted any other bombs before Monday's attack and whether they had the assistance or support of anyone else.
Anything Tsarnaev says to the team of FBI, CIA and Defense Department personel carrying out the interrogation will be admissible in court, despite Tsarnaev not having a lawyer on hand, NBC News reported.
Dzhokhar and his brother, 26-year-old Tamerlan, were identified by authorities and relatives as ethnic Chechens from southern Russia who had been in the U.S. for about a decade and were believed to be living in Cambridge, across the Charles River from Boston. Tamerlan Tsarnaev died in the shootout early Friday of gunshot wounds and a possible blast injury. At one point, he was run over by his younger brother in a car as he lay wounded, according to investigators.
During a long night of violence Thursday and into Friday, the brothers killed an MIT police officer, severely wounded another lawman during a gun battle and hurled explosives at police in a desperate getaway attempt, authorities said. That shootout left Tamerlan dead, while Dzhokhar escaped on foot.
Late Friday, less than an hour after authorities lifted a widespread lockdown they imposed to track down the younger brother, they receivied a crucial tip from a resident who had left his house to smoke and noticed that a tarp over the boat in the backyard was flapping, the resident's relative told NBC News. The man peered into the boat and saw a person curled up and wearing bloody clothes, then he ran inside to call police, the relative said.
Thermal imaging from police helicopters confirmed there was a person alive in the boat, officials said. After the discovery, bursts of gunfire could be heard in Watertown, as well as blasts from the police's flash-bang grenades. A police negotiator had also been brought to the scene.
Throughout the day Friday, police had scoured the city of Boston and its suburbs, uncovering seven more bombs and the grisly remnants of the overnight shootout.
As the manhunt dragged on, a portrait began to emerge of the Tsarnaev brothers, who relatives and authorities said immigrated to the U.S. with their ethnic Chechen family a decade ago.
The Kyrgyzstan-born suspect on the run, Dzhokhar Tsarnaev, became a U.S. citizen on Sept. 11, 2012, according to documents obtained by NBC News. The University of Massachusetts Dartmouth said he was registered as a student there.
The dead brother, Tamerlan, was born in Russia and became a legal U.S. permanent resident in 2007, authorities told NBC News. He had studied accounting as a part-time student at Bunker Hill Community College in Boston for three semesters from 2006 to 2008, the school said.
In 2011, Tamerlan came across the FBI's radar after a foreign government expressed concerns that he may have had links to terrorism, an official familiar with the matter told NBC News. The FBI investigated and reported back to the foreign government that no such ties were found, the official added.
Travel records obtained by NBC 4 New York show Tamerlan Tsarnaev flew into and out of John F. Kennedy Airport last year on Jan. 12 for a trip to Sheremetyevo, Russia. He stayed overseas and returned to JFK on July 17. The documents also show Dzhokhar Tsarnaev was born on July 22, 1993. They show he flew to the U.S. on April 12, 2002 with his family, which applied for asylum.
The U.S. Army said after a records check that neither had served in the active duty Army, guard or reserves
The parents of the Tsarnaev brothers told NBC News that their sons were framed.
"You could kill me but I would never believe they had anything to do with this," the father, Anzor Tsarnaev, said in a telephone interview from Dagestan's provincial capital, Makhachkala. "This is nonsense. It doesn’t add up."
The suspects' uncle Ruslan Tsarni told Today on Saturday that Dzhokhar Tsarnaev was used by his older brother and that both men were radicalized by others.
"I strongly believe they were just puppets and executors of something of bigger scale," said Tsarni, the brother of the suspects’ father. He added that the brothers spent time in his home as children and that he noticed a significant transformation the last time he saw Tamerlan in 2009.
“I was shocked when I heard his words, his phrases, when every other word he starts sticking in words of God," Tsarni said.
Tsarni said he was "angry" on Friday when he told reporters outside his home in Montgomery Village, Md. that his nephews were "losers."
After Tsarnaev was finally captured shortly after 8:30 p.m., celebration erupted throughout Boston and the rest of the country, which was closely watching events unfold.
"CAPTURED!!! The hunt is over. The search is done. The terror is over. And justice has won. Suspect in custody," Boston police tweeted.
"The people of the greater Boston area are going to be able to sleep tonight," Boston Mayor Thomas Menino said at a Friday night press conference after Tsarnaev's capture.