The surviving suspect in the Boston Marathon bombing lay hospitalized in serious condition under heavy guard _ apparently in no shape to be interrogated _ as investigators tried to establish the motive for the deadly attack and the scope of the plot.

People across the Boston area breathed easier the morning after Dzhokhar Tsarnaev, 19, was pulled, wounded and bloody, from a tarp-covered boat in a Watertown backyard. The capture came at the end of a tense day that began with his 26-year-old brother, Tamerlan, dying in a gunbattle with police.

There was no word Saturday on when Tsarnaev might be charged and what those charges would be. The twin bombings on Monday killed three people, including a Chinese student, and wounded more than 180.

The most serious charge available to federal prosecutors would be the use of a weapon of mass destruction to kill people, which carries a possible death sentence. Massachusetts does not have the death penalty.

President Barack Obama said there are many unanswered questions about the bombing, including whether the Tsarnaev brothers _ ethnic Chechens from southern Russia who had been in the U.S. for about a decade and lived in the Boston area _ had help from others. The president urged people not to rush to judgment about their motivations.

U.S. officials said an elite interrogation team would question the Massachusetts college student without first advising him of his right to remain silent and the right to an attorney. This exception to issuing the warning known as the Miranda rule typically given to criminal suspects is allowed on a limited basis when the public may be in immediate danger, such as instances in which bombs are planted and ready to go off.

The American Civil Liberties Union expressed concern about invoking the exception. Executive Director Anthony Romero said the 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 once he is charged. 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 Saturday afternoon that Tsarnaev was in serious but stable condition and was probably unable to communicate. Tsarnaev was at Boston’s Beth Israel Deaconess Medical Center, where 11 victims of the bombing were still being treated.

``I, and I think all of the law enforcement officials, are hoping for a host of reasons the suspect survives,‘’ Patrick said after ceremony before Saturday‘s baseball game at Fenway Park to honor the victims and survivors of the attack. ``We have a million questions, and those questions need to be answered.’‘

The all-day manhunt Friday brought the Boston area to a near standstill and put people on edge across the metropolitan area.

The break came around nightfall when a homeowner in Watertown saw blood on his boat, pulled back the tarp and saw a bloody Dzhokhar Tsarnaev hiding inside, police said. After an exchange of gunfire, police negotiated his surrender and he was seized and taken away in an ambulance.

Raucous celebrations erupted in and around Boston, with chants of ``USA! USA!’‘ Residents flooded the streets in relief four days after the two pressure-cooker bombs packed with nails and other shrapnel went off.

``Tonight, our family applauds the entire law enforcement community for a job well done, and trust that our justice system will now do its job,’‘ said the family of 8-year-old Martin Richard, who died in the bombing. Also killed in the attack was Lu Lingzi, a 23-year-old student from China, and Krystle Campbell, a 29-year-old restaurant worker.

The bloody endgame came just a day after the FBI released surveillance-camera images of two young men in baseball caps suspected of planting the explosives at the Boston Marathon finish line.

Queries cascaded in after authorities released the photos _ the FBI website was overwhelmed with 300,000 hits per minute _but what role those played in the overnight clash was unclear. State police spokesman Dave Procopio said police realized they were dealing with the bombing suspects based on what the two men told a carjacking victim during their night of crime.

During the long night of violence leading up to the capture, the Tsarnaev brothers carjacked a man in a Mercedes-Benz and released him unharmed, killed a Massachusetts Institute of Technology police officer, severely wounded another lawman and took part in a furious gun battle and car chase in which they hurled two hand grenades at police from a large homemade arsenal, authorities said.

Watertown Police Chief Edward Deveau said Tamerlan Tsarnaev ran out of ammunition and police tackled him, before Dzhokhar Tsarnaev drove the carjacking victim’s Mercedes towards them. Police dove out of the way and the Mercedes dragged the older brother‘s body down the block.

Police said three other people were taken into custody for questioning at an off-campus housing complex at the University of Massachusetts Dartmouth where Dzhokhar Tsarnaev may have lived.

Chechnya, where the Tsarnaev family has roots, has been the scene of two wars between Russian forces and separatists since 1994. That spawned an Islamic insurgency that has carried out deadly bombings in Russia and the region, although not in the West.

Investigators have not offered a motive for the Boston attack. But in interviews with officials and relatives and acquaintances of the Tsarnaev brothers, a picture has emerged of the older brother as someone embittered toward the U.S. and increasingly vehement in his Muslim faith.

The Russian FSB intelligence security service told the FBI in 2011 about information that Tamerlan Tsarnaev was a follower of radical Islam, two law enforcement officials said Saturday.

According to an FBI news release, a foreign government said that Tamerlan Tsarnaev appeared to be strong believer and that he had changed drastically since 2010 as he prepared to leave the U.S. for travel to a region in that country to join unspecified underground groups.

The FBI did not name the foreign government, but the two officials said it was Russia. The officials spoke on condition of anonymity because they were not authorized to talk about the matter publicly.

The FBI said that in response, it interviewed Tamerlan Tsarnaev and relatives, and did not find any domestic or foreign terrorism activity. The bureau said it looked into such things as his telephone and online activity, his travels and his associations with others.

An uncle of the Tsarnaev brothers said he had a falling-out with Tamerlan over the man’s increased commitment to Islam.

Ruslan Tsarni said Tamerlan told him in a 2009 phone conversation that he had chosen ``God‘s business’‘ over work or school. Tsarni said he then contacted a family friend who told him Tsarnaev had been influenced by a recent convert to Islam.

Tsarni said his relationship with his nephew ended after that call.

As for Dzhokhar Tsarnaev, ``he’s been absolutely wasted by his older brother. I mean, he used him. He used him for whatever he‘s done,’‘ Tsarni said.

Albrecht Ammon, a downstairs-apartment neighbor of Tamerlan Tsarnaev in Cambridge, Massachusetts, said in an interview that the older brother had strong political views about the United States. Ammon quoted Tsarnaev as saying that the U.S. uses the Bible as ``an excuse for invading other countries.’‘

Tamerlan Tsarnaev studied accounting as a part-time student at Bunker Hill Community College in Boston for three semesters from 2006 to 2008, the school said. He was married with a young daughter.

Dzhokhar Tsarnaev was a student at the University of Massachusetts Dartmouth. Students said he was on campus this week after the Boston Marathon bombing.

As of Saturday, more than 50 victims of the bombing remained hospitalized, three in critical condition. (AP)