MAKHACHKALA, Russia -- The parents of the two brothers accused in the bomb attack that killed three people and wounded more than 260 near the finish line of the Boston Marathon insisted on Thursday that their sons were innocent and had no connection to radical Islam.
In an outpouring of anguish and anger at a news conference here in the capital of Dagestan, the brothers' father, Anzor Tsarnaev, and mother, Zubeidat Tsarnaeva, also made accusations of a conspiracy in which the American authorities murdered their older son, Tamerlan, after seizing him.
Officials in the United States have said that Tamerlan was shot during a wild standoff with the police and was run over by a car driven by his younger brother as he escaped from the scene. The younger brother, Dzhokhar Tsarnaev, was captured and has been charged with using a weapon of mass destruction. He is recovering in a Boston hospital and may face the death penalty if convicted. Officials have also released video showing the brothers near the site of the marathon bombing.
Despite this evidence, and after two days of questioning by agents of the Federal Bureau of Investigation here, Ms. Tsarnaeva said she would not accept that her sons were guilty.
"No I don't -- and I won't," she snapped at the news conference. "Never!"
During an emotional, nearly hourlong question-and-answer session, the parents addressed many of the questions that investigators and the American public have been asking in the anxious, unsettled days after the bombing, insisting their sons were not religious radicals or connected to any terrorist organization.
Their answers were often a mixture of denial and conspiracy theory.
In one dramatic moment, Ms. Tsarnaeva said that F.B.I. agents who came to the family's home in Massachusetts to question Tamerlan about his religious views had asked her if she worried that he might commit an act of terrorism.
"Actually, they told me, don't you think that Tamerlan is being a little bit, you know, like, extreme about religion?" she said. "Do you think that he would think about organizing some kind of, you know ----" She broke off and stumbled over her words. "Probably that was their meaning: terroristic, terrorism or whatever, aggression."
"Do you see any aggression in Tamerlan?" she said, quoting the agents. "No, I did not. I did not. I really did not see any reason to worry."
Ms. Tsarnaeva said that she was considering giving up her American citizenship.
She said that in the days after the Boston bombing she had seen what she described as video footage on the Internet appearing to show Tamerlan alive and being put into a police car, naked, apparently stripped to check for explosives. The next day, she said, she saw gruesome images of his dead body.
"Killed, truly killed," she said, describing the images. "I wanted to scream, to scream to the whole world: 'What did you do? What have you done with my son?' He was alive. Why did they need to kill him? Why not send him to Guantánamo or whatever? Why did they kill him? Why did they have to kill him? They got him alive. He was in their hands."
The parents spoke alternately in Russian and English, sometimes starting a sentence in one language and finishing in the other. Mr. Tsarnaev wore dark sunglasses, while Ms. Tsarnaeva wore a head scarf, which is customary among many women in this predominantly Muslim region.
They said that they regretted having lived in the United States, but that they wanted to travel back soon see Dzhokhar, though they expressed fear that they would not be allowed to see him until he was put in prison.
"Yes, I would prefer not to live in America now. Like, why did I even go there -- why?" Ms. Tsarnaeva said, nearly breaking into tears. "I thought America was going to, like, protect us, our kids, it was going to be safe for any reason. But it happened the opposite. My kids -- America took my kids away from me -- only America. So why wouldn't I regret? Why?"
"I don't know," she said, regaining her composure. "I am sure that my kids were not involved in anything."
Anzor Tsarnaev responded sharply to a reporter who asked why Tamerlan had felt that he did not fit in among Americans, once saying he did not have any friends.
"That's not true," Mr. Tsarnaev said. "He have a lot of friends. I know these friends."
Ms. Tsarnaeva jumped in to say that Tamerlan had meant he did not have a best friend. "It does not mean that he did not fit in America," she said.
The parents said the F.B.I. agents who questioned them had been most interested in Tamerlan's six-month visit to Dagestan last year, which they said had been undertaken so that he could obtain a Russian passport. Although he was born in Russia, Tamerlan had traveled on a passport from Kyrgyzstan, where the family lived, that was about to expire. They said he needed a Russian passport because he did not have American citizenship.
Ms. Tsarnaeva reacted furiously to a questioner who said Dzhokhar had told officials the brothers were motivated by extremist Islam. "I'll answer," she said. "They told me yesterday that he was not questioned yet," she said of her son's lawyers. "Where does this information come from? Where does this information come from?"
"Where does this information come from?" she shouted again.
Andrew Roth and Viktor Klimenko contributed reporting from Makhachkala.
Correction: April 25, 2013, Thursday
This article has been revised to reflect the following correction: An earlier version of this article misspelled, on one reference, the younger suspect's first name. It is Dzhokhar, not Dzhokar.
This article originally appeared in The New York Times.