THE wife of deceased Boston Marathon suspect Tamerlan Tsarnaev saw her husband just hours before his death, but had no idea of any plot, her lawyers said.

Katherine Russell last saw her husband on Thursday night, just hours before he was killed in a police shoot-out, her lawyer told CNN. She was handing over their two-year-old daughter to him before heading to work.

"She knew nothing about it at any time," her lawyer Amato DeLuca told CNN. He said Ms Russell learned about her husband's involvement on the news, and is "is very distraught" and "cries a lot".

"The whole family is a mess, to put it bluntly," said Mr DeLuca. "They're very distraught. They're upset. Their lives have been unalterably changed. They're upset because of what happened, the people that were injured, that were killed. It's an awful, terrible thing."

American-born Ms Russell met Tamerlan as a uni student, prompting her to convert to Islam and drop out of college, friends said. The pair were married in June, 2010.

Meanwhile, Dzhokhar Tsarnaev's condition has been upgraded to fair, the US District Attorney's office said. Dzhokhar, younger brother of Tamerlan, was yesterday charged with the bomb attack and has been communicating with officials.

It has also emerged that Tamerlan Tsarnaev was an ardent reader of jihadist websites and extremist propaganda, US officials said, adding another piece to the body of evidence they say suggests he and his younger brother Dzhokhar were motivated by an anti-American, radical version of Islam.

Two officials said the older brother frequently looked at extremist sites, including Inspire magazine, an English-language online publication produced by al-Qaida's Yemen affiliate. The magazine has endorsed lone-wolf terror attacks.

Earlier, bombing suspect Dzhokhar Tsarnaev uttered his first word after being charged with using a weapon of mass destruction - "No".

The 19-year-old, who could face the death penalty if convicted, was mostly silent and nodded affirmatively throughout the brief bedside hearing, indicating that he understood the charges laid against him, court transcripts published by The New York Times reveal.

But when asked if he could afford a lawyer, the teen spoke for the first time, saying: "No".

Details of Tsarnaev's bedside hearing came amid reports that the teen reportedly told investigators his older brother and alleged co-conspirator Tamerlan was the driving force behind the bombings.

CNN says Tsarnaev, who has an injury to his throat, has communicated he and his brother acted alone and that Tamerlan, the older of the two, was the ringleader in the bombings.

The teen told investigators that no international terrorist groups were behind the act and that his elder brother carried out the bombings as he wanted to defend Islam from attack.

However, the written communication precluded back-and-forth exchanges often crucial to establishing key facts, officials said. They warned that they were still trying to verify what Tsarnaev told them and were poring over his telephone and online communications.

Tsarnaev's answers led officials to believe he and his brother were motivated by religious extremism but appeared to have no major terrorist group connections, said US officials, who spoke on condition of anonymity because they were not authorized to discuss the investigation publicly.

CNN reported that preliminary interviews indicate the two brothers fit the classification of self-radicalised jihadists. CNN says the pair's radicalisation had an online component as they watched videos on the internet.

Read: The FBI case against Dzhokhar Tsarnaev

Dzhokhar Tsarnaev's brief bedside proceeding began when Judge Marianne Bowler asked a doctor whether Tsarnaev was alert, according to the summary of proceedings provided by the court.

"You can rouse him,” the judge told the doctor.

A doctor, identified in the transcript as Dr Odom, asked Tsarnaev how he was feeling.

"Are you able to answer some questions?" the doctor asked the teen.

Tsarnaev "nods affirmatively," according to the document, the first of four times during the hearing.

The only word Dzhokhar Tsarnaev uttered apparently was "No," after he was asked if he could afford a lawyer.

Judge Bowler said: "Let the record reflect that I believe the defendant has said, 'No.'"

Tsarnaev was charged with using a weapon of mass destruction and also has been charged with one count of malicious destruction of property by means of deadly explosives.

The next step in the legal process against Tsarnaev is likely to be an indictment, in which federal prosecutors could add new charges. State prosecutors have said they expect to charge Tsarnaev separately in the killing of a Massachusetts Institute of Technology police officer who was shot in his cruiser Thursday night on the campus in Cambridge.

A probable cause hearing - at which prosecutors will spell out the basics of their case - was set for May 30. According to a clerk's notes of Monday's proceedings in the hospital, Judge Bowler indicated she was satisfied that Tsarnaev was "alert and able to respond to the charges."

Federal public defender Miriam Conrad, whose office has been asked to represent Tsarnaev, asked that two death penalty lawyers be appointed to represent Tsarnaev, "given the magnitude of this case."

The charges came shortly before Boston held a moment of silence at 2.50pm on Monday (4.50am Tuesday AEST) in honour of the three people killed and 180 wounded in the twin bombing of the city's marathon exactly one week ago. Church bells tolled across the city and state in tribute to the victims.

US President Barack Obama also observed the moment of silence, as did the New York Stock Exchange. It was to be followed by a ceremony to honour first responders and police.

Hundreds gathered outside the security cordon set up near the blast sites at the marathon finish line on Boylston Street to honour the dead and wounded. Some prayed while others silently took video footage of the occasion.

Some left flowers tied together with purple or white ribbons at a makeshift memorial.

The federal charges against Tsarnaev "authorise a penalty, upon conviction, of death or imprisonment for life or any term of years," the statement said.

"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 US 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."

Tsarnaev and his older brother Tamerlan, 26, who was killed in a shootout with police, are accused of the twin bombing at the Boston Marathon.

The White House said Tsarnaev would not be treated as an "enemy combatant" but would be tried through the US civilian federal court system.

"He will not be treated as an enemy combatant," said White House spokesman Jay Carney, following calls from some Republicans for 19-year-old Tsarnaev to be granted the same status as "War on Terror" detainees.

Tsarnaev, who was born in Russia, is a naturalised US citizen. Under US law, US citizens cannot be tried in military commissions, Mr Carney said. Since Sept. 11, 2001, the federal court system has been used to convict and incarcerate hundreds of terrorists, he said.

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.

After the first explosion ripped through the crowd, a calm-looking Tsarnaev quickly walked away, and about 10 seconds later, the second blast occurred where he left the knapsack, the FBI said.

The FBI did not make it clear whether authorities believe he used his cellphone to detonate one or both of the bombs or whether he was talking to someone.

The court papers also said that during the long night of crime Thursday and Friday that led to the older brother's death and the younger one's capture, one of them told a carjacking victim: "Did you hear about the Boston explosion? I did that."

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 one of the suspected bombers in the surveillance photos the FBI released a few days after the attack.

The first hearing in US federal court in the case against Dzhokhar Tsarnaev has been scheduled for May 30, an official in the US prosecutor's office in the city said. It was not clear if Tsarnaev would be present.

He is also likely to face state charges in the shooting death of MIT police officer Sean Collier.

The charge comes as the man who was carjacked by Dzhokhar and Tamerlan Tsarnaev told police the brothers told him they wouldn't kill him because he "wasn’t American."

The man was carjacked and abducted by the brothers before their shootout with police, which left elder brother Tamerlan Tsarnaev dead. The carjacking victim, who asked to remain anonymous, told NBC News the pair were "brutal and cautious".

In other startling development, authorities are now investigating whether Tamerlan Tsarnaev was involved in the gruesome, unsolved triple homicide of a former roommate and two other people. The murders took place in 2011, around the tenth anniversary of the 9/11 attacks.

The victims were found with their throats slashed in what one investigator told US ABC News was “the worst bloodbath I have ever seen.”

“We are looking at a possible connection with the suspect in the marathon atrocity and this active and open homicide in Waltham,” Middlesex District Attorney Stephanie Guyotte told US ABC News.

Keen boxer Tsarnaev often trained with one of the victims, Brendan Mess, 25, but did not attend his funeral.

Also overnight, it was revealed that the FBI missed Tamerlan Tsarnaev's five-month trip to Russia in 2011-2012 because his name was misspelled.

Many Boston residents headed back to workplaces and schools for the first time since a dramatic week came to an even more dramatic end. Traffic was heavy on major arteries into the city on Monday morning, and nervous parents dropped their children off at schools, some for the first time since the attacks.

Authorities on Friday had made the unprecedented request that residents stay at home during the manhunt for suspect Dzhokhar Tsarnaev. He was discovered that evening hiding in a boat covered by a tarp in suburban Watertown.

At the Snowden International School on Newbury Street, a high school set just a block from the bombing site, jittery parents dropped off children as teachers - some of whom had run in the race - greeted each other with hugs.

Carlotta Martin, 49, of Boston, said that leaving her kids at school has been the hardest part of getting back to normal.

"We're right in the middle of things," Ms Martin said outside the school as her children, 17-year-old twins and a 15-year-old, walked in, glancing at the police barricades a few yards from the school's front door.

"I'm nervous. Hopefully, this stuff is over," she continued. "I told my daughter to text me so I know everything's OK."

The city is beginning to reopen sections of the six-block site around the bombing that killed three people and wounded more than 180.

Outside City Paint, the paint store a half-block from the brothers' home, Brian Cloutier smoked a cigarette. "We'll get back to normal," he said. "Cambridge and Boston are resilient."

A private funeral was scheduled for Krystle Campbell, a 29-year-old restaurant worker killed in the blasts. A memorial service will be held that night at Boston University for 23-year-old Lu Lingzi, a graduate student from China.

City churches on Sunday paused to mourn the dead as the city's police commissioner said the two suspects had such a large cache of weapons that they were probably planning other attacks.

After the two brothers engaged in a gun battle with police early Friday, authorities found many unexploded homemade bombs at the scene, along with more than 250 rounds of ammunition.

Police Commissioner Ed Davis said the stockpile was "as dangerous as it gets in urban policing".

"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. That's my belief at this point." Mr Davis told CBS television.



On Fox News Sunday, he said authorities cannot be positive there are not more explosives somewhere that have not been found. But the people of Boston are safe, he insisted.

Dzhokhar Tsarnaev and his 26-year-old brother, Tamerlan, the suspects in the twin bombings, are ethnic Chechens from southern Russia. The motive for the bombings remained unclear.

Senator Dan Coats of Indiana, a member of the Senate Intelligence Committee, said the surviving brother's throat wound raised questions about when he will be able to talk again, if ever.

The wound "doesn't mean he can't communicate, but right now I think he's in a condition where we can't get any information from him at all," Senator Coats told This Week, on US network ABC.

It was not clear whether Tsarnaev was shot by police or inflicted the wound himself.

In the final standoff with police, shots were fired from the boat, but investigators have not determined where the gunfire was aimed, Mr Davis said.

In an interview with The Associated Press, the parents of Tamerlan Tsarnaev insisted he came to Dagestan and Chechnya last year to visit relatives and had nothing to do with the militants operating in the volatile part of Russia. His father said he slept much of the time.

A lawyer for Tamerlan Tsarnaev's wife said federal authorities have asked to speak with her, and that he is discussing with them how to proceed.

Attorney Amato DeLuca said Katherine Russell Tsarnaev did not suspect her husband of anything, and that there was no reason for her to have suspected him. He said she had been working 70 to 80 hours, seven days a week, as a home health care aide. While she was at work, her husband cared for their toddler daughter, he said.

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives was tracing the suspects' weapons to try to determine how they were obtained.

Neither of the brothers had permission to carry a gun. Cambridge Police Commissioner Robert Haas said it was unclear whether either of them ever applied for a gun permit, and the applications are not considered public records.

But the younger brother would have been denied a permit based on his age alone. Only people 21 or older are allowed gun licenses in Massachusetts.

Meanwhile, surgeons at a Cambridge hospital said the Boston transit police officer wounded in a shootout with the suspects had lost nearly all his blood, and his heart had stopped from a single gunshot wound that severed three major blood vessels in his right thigh.

Richard Donohue, 33, was in critical but stable condition. He is sedated and on a breathing machine but opened his eyes, moved his hands and feet and squeezed his wife's hand on Sunday.

