Transcript for Gunpowder in Boston Bombs Likely from Fireworks
investigation. There's new details this morning on the condition of the suspect still recovering in the hospital. He's been improved to fair condition. But what was inside the bombs and what his mother is saying, now, about the bombings and the charges. Abc's brian ross has the latest on all of that. Good morning to you, brian. Reporter: Good morning, elizabeth. Law enforcement officials continue to question whether others were involved in the boston attack. Despite the claims of the surviving brother to the fbi, that the two of them acted alone. And overnight, there are new details of the attack had been in the planning stages for at least twmonths. A new hampshire fireworks store has told the fbi, it sold $400 worth of fireworks in february to tamerlan tsaranev. The gun powder and fireworks was likely the explosives used in the marathon bombs, according to bomb experts. The assistant manager of phantom fireworks, tsaranev bought two large mortar kits. And she remembers his russian accent. We don't get too many people in here with russian accents. Reporter: Meanwhile, the medical condition of younger brother dzhokhar has been upgraded from serious to fair. And so of his friends are trying to upgrade his image. One friend posted t video on youtube, showing dzhokhar doing the robot dance with buddies on the wrestling team. Friends ask if he was a hard-core islamic terrorist, or a brainwashed teenager, under the sway of his big brother, tamerlan. The older brother appeared to be more radicalized of the two. And was the one that drove the need to conduct the attacks as well as the preparation for the attacks themselves, building the bombs. Reporter: Tamerlan's wife karina remained out of sight. Involvement like her husband and brother-in-law came as an absolute shock to them all. Reporter: There was little sympathy from any of the tsaranev family tuesday, at the funeral of the police officer, who was allegedly killed by the two brothers last thursday on the m.I.T. Campus. He was killed at point-blank range. They're evil. Reporter: In russia, the mother of the brothers tsaranev, zubeidat, was defiant in claiming her son's innocence. My son was muslim. That's it. What happened is a terrible thing. But I know that my kids have nothing to do with this. I know it. I am mother. Reporter: The mother says she may come to the united states to see her surviving son and claim the body of her dead one. But if she does, she faces possible arrest for failing to appear in court in boston last october on charges she shoplifted some $1,600 in clothing from the lord & taylor department store. That's a lot of clothing. A lot of clothing. Brian, thank you so much.
This transcript has been automatically generated and may not be 100% accurate.