With the surviving suspect in the Boston Marathon bombings lying seriously wounded in a hospital, investigators worked on Saturday to determine a motive and whether the ethnic Chechen brothers accused in the attack acted alone.
Dzhokhar Tsarnaev, 19, was captured late on Friday after a gunfight with police that ended a daylong manhunt and sent waves of relief and jubilation throughout Boston. His brother Tamerlan, 26, was killed on Thursday in a shootout with police.
Tsarnaev was being treated at Beth Israel Deaconess Medical Center in Boston, said spokeswoman Kelly Lawman, who said the FBI would provide updates on his condition.
It was not clear when he would be charged.
The brothers are suspected of setting off bombs made in pressure cookers and packed with ball bearings and nails at the crowded finish line of the marathon, killing three people and injuring 176.
After Monday's deadly bombings and the manhunt that shut down the Boston metropolitan area for most of Friday, life on Saturday regained some sense of normalcy.
Boston's Red Sox baseball team returned to Fenway Park for the first time since the bombings, paying an emotional tribute to the victims and the first responders before the game against the Kansas City Royals.
Tsarnaev had been hiding in a boat parked in the backyard of a house in the suburb of Watertown, police said. A resident called police after spotting blood on the boat. Police said he was bleeding and in serious condition when admitted to the hospital.
President Barack Obama said after the capture that questions remained from the bombings, including whether the two suspects received any help.
Early indications are that the brothers acted alone, Watertown Police Chief Edward Deveau told CNN on Saturday.
"From what I know right now, these two acted together and alone," he said. "But as far as this little cell or this little group, I think we got our guys."
Monday's bombing at the world-famous marathon was described by Obama as an act of terrorism.
On Saturday, several Republican lawmakers called on the Obama administration to try Tsarnaev as an "enemy combatant" under terms of war, without entitlement to Miranda rights or appointment of counsel.
"The accused perpetrators of these acts were not common criminals attempting to profit from a criminal enterprise, but terrorists trying to injure, maim, and kill innocent Americans," Senators John McCain of Arizona, Lindsey Graham of South Carolina and Kelly Ayotte of New Hampshire, and Representative Peter King of New York said in a statement.
Authorities did not read the teenager the Miranda warning usually given by police to criminal suspects before they are interrogated so statements can be admissible in court.
A Justice Department official said the government is invoking the public safety exception to Miranda to question the suspect extensively about other potential explosive devices or accomplices and to gain critical intelligence.
The Republicans lawmakers praised that decision and also said they were encouraged that a so-called high-value detainee interrogation team was involved in the investigation.
The group was created by the Obama administration after the president ordered the shutdown of a CIA program in which militant suspects were held in a network of secret prisons during the administration of President George W. Bush.
FBI INTERVIEWED SUSPECT IN 2011
The brothers had not been under surveillance as possible militants, U.S. government officials said. But the FBI said on Friday that it interviewed Tamerlan in 2011 at the request of a foreign government, which it did not identify.
A law enforcement source said that country was Russia.
"The request stated that it was based on information that he was a follower of radical Islam and a strong believer, and that he had changed drastically since 2010 as he prepared to leave the United States for travel to the country's region to join unspecified underground groups," the FBI statement said.
The matter was closed when the FBI "did not find any terrorism activity, domestic or foreign."
The FBI statement was the first evidence that the family had come to security officials' attention after they emigrated to the United States about a decade ago.
Tamerlan was charged in July 2009 with domestic assault and battery of his girlfriend, but was not convicted, said a spokeswoman for the Middlesex District Attorney's office.
The brothers spent their early years in a small community of Chechens in the central Asian country of Kyrgyzstan, a mainly Muslim nation of 5.5 million. The family moved in 2001 to Dagestan, a southern Russian province that lies at the heart of a violent Islamist insurgency and where their parents now live.
In separate interviews, the parents of the Tsarnaev brothers said they believed their sons were incapable of carrying out the bombings. Others remembered the brothers as friendly and respectful youths who never stood out or caused alarm.
"Somebody clearly framed them. I don't know who exactly framed them, but they did. They framed them. And they were so cowardly that they shot the boy dead," father Anzor Tsarnaev said in an interview with Reuters in Dagestan's provincial capital, Makhachkala, clasping his head in despair.
The mother, Zubeidat Tsarnaeva, told Russia Today state television: "It's impossible, impossible, for both of them to do such things, so I am really, really, really telling that this is a setup."
But Ruslan Tsarni, who said he was an uncle of the brothers, told CNN on Saturday that he first noticed a change in Tamerlan Tsarnaev's religious views in 2009. He said the radicalization of his nephew happened "in the streets of Cambridge."
BOSTON LOCKED DOWN IN MANHUNT
The Russian-installed leader of Chechnya criticized police in Boston for killing an ethnic Chechen and blamed the violence on his upbringing in the United States.
The Islamic Society of Boston Cultural Center, the biggest mosque in the area, said in a statement that it was shutting its doors until further notice.
The bombings prompted contact between the United States and Russia on terrorism and the Kremlin said on Saturday that the presidents of both had agreed by telephone to increase cooperation on counter-terrorism.
After combing through a mass of pictures and video from the site in the minutes before the Boston marathon bombing, the FBI publicized pictures of the two men on Thursday and asked the public for help in identifying them.
Just hours later, events began to unfold with the fatal shooting of a police officer on the campus of the Massachusetts Institute of Technology and finally the Watertown firefight, during which police say the brothers threw bombs at officers. Tamerlan suffered fatal wounds, while Dzhokhar escaped on foot.
The hunt for Tsarnaev emptied Boston's streets as the city went into lockdown for most of Friday. Public transportation was suspended and air space restricted. Famous universities, including Harvard and MIT, closed after police told residents to remain at home.