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Boston Marathon bombing suspect Dzhokhar Tsarnaev remained in serious condition at a Boston hospital under heavy guard Sunday as investigators continued the long process of looking over motives, methods and possible links.

Tsarnaev, 19, who was taken into custody on Friday and whose older brother, Tamerlan, was killed in a shootout with police, will be questioned by a special team sent in by the FBI, Boston Police Commissioner Ed Davis told “Fox News Sunday.”

“He’s [Dzhokhar] in no condition to be interrogated at this point in time. He’s progressing, though, and we’re monitoring the situation carefully," Davis said.

Massachusetts Gov. Deval Patrick said Saturday Dzhokhar 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," the governor said after a ceremony 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 twin bombings killed three people and wounded more than 180.

Patrick told NBC on Sunday that surveillance video clearly puts Dzhokhar Tsarnaev at the scene of the attack.

"It does seem to be pretty clear that this suspect took the backpack off, put it down, did not react when the first explosion went off and then moved away from the backpack in time for the second explosion," Patrick said. "It's pretty clear about his involvement and pretty chilling, frankly."

Investigators believe the suspects also were likely planning other attacks based on the cache of weapons uncovered during the Thursday night shootout, according to Davis.

"We have reason to believe, based upon the evidence that was found at that scene -- the explosions, the explosive ordnance that was unexploded and the firepower that they had -- that they were going to attack other individuals," Davis said Sunday on CBS' "Face the Nation". "That's my belief at this point."

Davis added on "Fox News Sunday" that authorities cannot be positive there aren't more explosives that haven't been found, but the people of Boston are safe.

There was no immediate word on when Tsarnaev might be charged and what those charges would be, but a source told Fox News charges wouldn't come Sunday.

But 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.

A Justice Department official said Friday the government is invoking a seldom-used public safety exception permitting officials to engage in a limited and focused unwarned interrogation of a suspect -- in this case Dzhokhar Tsarnaev -- without first reading him his typically assured Miranda rights. That official, as well as a second, both of whom spoke on the condition of anonymity, says Tsarnaev will be questioned by a special interrogation team for high-value suspects.

The public safety exception not only permits the unwarned questioning of a suspect, but also allows the government to introduce any statement yielded by such interrogation as evidence in court. The exception is triggered when authorities have an objectively reasonable need to protect themselves or the public from a clear and present danger.

However, the exception lasts only 48 hours and should be extended by declaring Tsarnaev a potential enemy combatant, under the Law of War, Republican Sens. Lindsey Graham, South Carolina; John McCain, Arizona; and Kelly Ayotte, New Hampshire, said in a statement Saturday. They were joined by New York Republican Rep. Peter King.

A lawyer for the wife of Tamerlan Tsarnaev said Sunday federal authorities have asked to speak with his client as part of their investigation.

Authorities went to the suburban Rhode Island home of Tsarnaev's in-laws Sunday evening, where Katherine Russell Tsarnaev has been staying. Lawyer Amato DeLuca tells The Associated Press that she did not speak with them, and they are discussing how to proceed.

DeLuca says Tsarnaev did not suspect her husband of anything, and nothing seemed amiss after the bombings. He says she had been working 70 to 80 hours a week as a home health care aide, while her husband cared for their daughter.

DeLuca says on the day he died, Tamerlan Tsarnaev was home when his wife left for work, and that the couple married in 2009 or 2010.

According to media accounts, Tsarnaev and his brother, Tamerlan, were Muslims who recently gravitated to a radical strain of Islam, going so far as to post Anti-American, jihadist videos on social-media sites. Both are thought to have as-yet-unprobed ties to a radical Muslim cleric hellbent on the destruction of the American way of life.

A day-long dragnet for Tsarnaev ended Friday, with police capturing the suspect covered in blood and hiding in a boat in the backyard of a man who called 911 after becoming suspicious of activity on his property.

"We got him," Boston Mayor Tom Menino tweeted moments later, as neighbors gathered to form a gauntlet of cheers while a phalanx of police cars departed the scene.

Police moved in on Dzhokhar Tsarnaev Friday evening after a tip led them to the home on Franklin Street.

Neighbors said they heard more than 30 shots likened to "a roll of firecrackers shooting off." Police swarmed the scene, and several explosions, possibly police concussion grenades, were heard after a robot moved in on the boat. Less than two hours later, at about 9 p.m., the suspect, believed to have been injured in a wild shootout that spanned Thursday night to Friday morning, was being taken to Beth Israel Hospital.

No police were injured when shots were fired by the boat.

Sources told Fox News the shed and the boat had been searched earlier, but a local man noticed a door to it had been opened, saw blood on the tarp and called police.

"It was a call from a resident of Watertown," Watertown Police Chief Edward Deveau said. "We got that call, and we got the guy."

Davis said Tsarnaev was in serious condition and was found "covered with blood." He did not come out from inside the boat willingly, despite the efforts of negotiators, Davis said.

"We assume that those injuries came from the gunfire the night before," Davis said. He also said Tsarnaev did not have any explosives with him when he was taken into custody.

The hiding place was found just moments after police said their hunt for Tsarnaev, one of two radical Muslim brothers suspected in Monday's attack, had gone cold and urged people to "go about your business."

Shortly after the capture was announced, Watertown residents poured out of their homes and lined the streets to cheer police vehicles as they rolled away from the scene.

Celebratory bells rang from a church tower. Teenagers waved American flags. Drivers honked. Every time an emergency vehicle went by, people cheered loudly.

"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.

Early in the day, police told residents of several city neighborhoods, especially Watertown, to stay inside. School was canceled, bus and train service suspended and people were even told not to venture out for work. But those restrictions were lifted at the news briefing Friday night about 15 minutes before the gunshots were heard.

The boat Tsarnaev hid under was just outside the tight perimeter where Black Hawk helicopters patrolled the sky and police went door-to-door hunting for him, police said. Police say he and his older brother placed the deadly bombs, at least one of which was made from a pressure cooker packed with explosives and shrapnel, at the race, killing three and injuring more than 180. The sibling suspects are from Dagestan, a province in Russia that borders Chechnya, but have been in the U.S. for as much as a decade..

On Thursday night, hours after the radicalized Muslims were fingered by the FBI and their images circulated around the world, they killed a Massachusetts Institute of Technology police officer and carjacked an SUV from a man who later escaped. The brothers led police on a chase through city streets that included a wild shootout that saw some 200 shots fired and the suspects hurling pipe bombs from the SUV. Bizarrely, police discounted earlier reports that the brothers had robbed a 7/11, saying although it had been robbed, and they had been caught on surveillance video, they were not the robbers.

The pursuit went into Watertown, where Tamerlan Tsarnaev, 26, was shot several times in the gunfight. But Dzhokhar Tsarnaev somehow slipped away, running over his already wounded brother as he fled by car, according to two law enforcement officials who spoke to The Associated Press on condition of anonymity. Tamerlan Tsarnaev was pronounced dead at Beth Israel Hospital Deaconess Medical Center Friday morning. But at some point following the shootout and car chase, the younger brother fled by foot, according to State Police, who said Friday night they don't believe he now has access to a car.

During the pursuit, a MBTA transit police officer was seriously injured and transported to the hospital, according to a news release. He was identified as Richard H. Donahue Jr., 33, and was at Mount. Auburn Hospital in critical but stable condition.

The suspects' bloody rampage claimed the life of MIT Police Officer Sean Collier, 26, who was found shot to death in his squad car at 10:20 p.m. Thursday in what Davis termed a "vicious assassination."

Moments after the shooting, the brothers carjacked the Mercedes SUV from Third Street in Cambridge and forced the driver to stop at several bank machines to withdraw money. The driver later told police that the brothers had bragged to him that they were the marathon bombers, law enforcement authorities said.

“The guy was very lucky that they let him go,” Massachusetts State Police spokesman David Procopio said.

It was when police were working to activate the tracking device on the stolen SUV, that other patrol officers spotted it in nearby Watertown, touching off the dramatic chase.

FBI Special Agent Rick Deslauriers said Friday night the FBI pored though thousands of tips, and chased down countless leads in the intense probe following the terror attack on Monday.

"The was a truly intense investigation," Deslauriers said. "As a result of that justice is being served for each of the victims of these crimes."

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Fox News' Jennifer Griffin, Jana Winter, Mike Tobin, Mike Levine, Griff Jenkins and The Associated Press contributed to this report.