Boston Marathon suspect Dzhokhar Tsarnaev's friends "don't believe" he did it

Updated at 10:46 a.m. ET

One of the teenagers accused of helping Boston Marathon bombing suspect Dzhokhar Tsarnaev in the wake of last month's deadly attack told his father that they doubted Tsarnaev was behind the blasts, the father said in a television interview.

Federal prosecutors charged 19-year-olds Dias Kadyrbayev and Azamat Tazhaykov, of Kazakhstan, with conspiracy to obstruct justice Wednesday, accusing Tsarnaev's friends from the University of Massachusetts at Dartmouth of disposing of his laptop computer and a backpack filled with fireworks after the bombing.

On "CBS This Morning" Thursday, CBS News correspondent Elaine Quijano reported from Boston that investigators recovered the laptop and the backpack last week in a New Bedford, Mass., landfill.

"They don't believe, they still don't believe, that he did that," Kadyrbayev's father Murat Kadyrbayev told Kazakhstan Channel 7 last week, according to a translation from the Reuters news service.

At the time, Kadyrbayev and Tazhaykov were being held over allegations of violating their student visas. On Wednesday, they did not enter a plea before a federal magistrate judge in Boston and are being held in federal custody along with Robel Phillipos, a Massachusetts man accused of making false statements to federal law enforcement officials.

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Murat Kadyrbayev said Dias told him that Tsarnaev, who has been charged in the attack and continues to recover in a federal prison medical facility from a shootout with authorities, didn't seem the violent type.

"He said, 'Daddy, we didn't know,'" the older Kadyrbayev said. "'He's not the kind of guy who would hurt anyone or do something else. There are those kind of 100 percent naturalized Americans. He was that kind. Very chatty.' He said, 'We were shocked.'"

The father said his family was "shocked" that Dias had been arrested at all.

"Everyone knows my son," the father said. "He's never fought anyone. He's never been in touch with any radicals. He doesn't go to the mosque, unless we go or there's another reason. In the U.S. he has never been to a mosque."

Kadyrbayev and Tazhaykov each face a maximum sentence of five years in prison. On "CBS This Morning" Thursday, CBS News legal analyst Jack Ford, a former prosecutor, said prosecutors will likely use the federal charges to get the teens to cooperate.

"If I'm the prosecutor, I'm saying to their lawyers, 'Look, you guys want to help yourselves here?'" Ford said. "'Here's what you got to do: Start thinking back. What did you see? What did you hear? Was there some conversation, something that maybe didn't strike you as being important back then might be helpful for you right now.'"