BOSTON The surviving suspect in the Boston Marathon attacks told federal agents that he and his late brother were motivated by extremist Islamic beliefs but that they were not connected to any known terrorist groups, law enforcement officials said Tuesday, saying that he made those statements in an interview Sunday from his hospital bed.
The investigators have been conducting a wide-ranging inquiry into the two brothers, speaking with people who knew them and looking at everything from the things they left behind in their homes and a dorm room to the digital trail they left through emails and social media.
Based on the inquiry so far and on the interview conducted with the sole surviving suspect, Dzhokhar Tsarnaev, 19, in which law-enforcement officials said that he acknowledged playing a role in the attacks the officials believe that the two men acted alone in the attacks, which killed three and injured more than 260.
Part of the investigation is now focused on corroborating Dzhokhar Tsarnaev's statements. His older brother, Tamerlan Tsarnaev, 26, was killed early Friday morning after a shootout with the police in Watertown, Mass.
Outside the home of the Tsarnaev brothers' parents in Makhachkala, Russia, friends of the family told reporters Tuesday that their mother, Zubeidat Tsarnaeva, had grown distraught after seeing a photograph of the dead body of their older son, Tamerlan, on television.
Kheda Saratova, a well-known Chechen human rights activist and friend of the family, told reporters: "Please don't torture this family, they want to wait awhile, they are in terrible grief. Please.
"We must defend this family while the case is being investigated, so we can't say anything for now," she said.
Tsarnaeva, who has given a number of interviews in recent days, walked out from behind her wearing a bright yellow head scarf, and made her way, through a scrum of photographers and reporters, to hail a taxi. "My son is just my son," she said in English.
In Boston, meanwhile, Martin Richard, the 8-year-old boy killed in the bombings, was remembered at a private funeral with his immediate family on Tuesday.
"The outpouring of love and support over the last week has been tremendous," said his parents, Bill and Denise, in a statement distributed by a family spokesman. "This has been the most difficult week of our lives and we appreciate that our friends and family have given us space to grieve and heal."
The family said they planned to hold a public memorial for Martin in the coming weeks.
And in Stoneham, roughly 12 miles outside of Cambridge, Mass., some 200 officers arrived at a funeral home on Common Street on Tuesday to pay their respects to the family of Sean Collier, a campus police officer at the Massachusetts Institute of Technology who was shot and killed last Thursday night. Law-enforcement officials have said that they believe that the Tsarnaev brothers were responsible for his death, but have not said what evidence leads them to believe that.
Hundreds of family and friends later flowed into nearby St. Patrick's Church for a private funeral Mass that began at 10 a.m., according to a spokeswoman for the Anderson-Bryant Funeral Home.
The information on the motive behind the bombing came as specially trained FBI agents interviewed Tsarnaev on Sunday as he recovered in a Boston hospital bed from gunshot wounds to the head, neck, legs and hand that he sustained in the shootout with police officers early Friday morning that left his brother dead. One law enforcement officer said that Tsarnaev's neck wound appeared to be the result of a self-inflicted gunshot.
The agents had been waiting outside his hospital room for him to regain consciousness. After he woke up, they questioned him, invoking what is known as the public safety exception to the Miranda Rule, a procedure authorized by a 1984 U.S. Supreme Court decision that in certain circumstances allows interrogation after an arrest without notifying a prisoner of the right to remain silent.
The bombings, which killed three people, injured more than 260 people far more than the 170 injured people that the authorities initially reported, officials said Tuesday. The revised figures are based on reports that the Boston Public Health Commission has received from 26 hospitals in the Boston area.
"We have seen a steady increase in the number of patients," Nick Martin, a spokesman for the Boston Public Health Commission said on Tuesday morning, adding that some people who were injured, but not seriously, had not sought medical care immediately. "An example is people with hearing problems who might have initially assumed it was a temporary issue. But it lasted longer than they thought it would."
As the new details over the motivation behind the bombings and the devastation they wrought emerged, there were signs that life in Boston was returning to normal.
Block by block, a stretch of Boylston Street in the heart of Boston's Back Bay neighborhood began to reopen on Tuesday, more than a week after the deadly bombings had turned it into a crime scene. And the Boston Police Department began returning property that people had left behind as they fled from the bombings.