Both brothers were born in Kyrgyzstan, according to their uncle, Ruslan Tsarni, who said he has not seen his nephews since December 2005. The uncle was angry over what his nephews are accused of doing.
The enraged uncle said the only explanation for their behavior is "hatred to those that were able to settle themselves" and "being losers."
"If you are alive, turn yourself in and ask for forgiveness from the victims, from the injured and from those who left," Tsarni shouted, delivering a message to his nephew. "He put a shame on our family. He put a shame on the entire Chechen enthnicity."
John Curran, Tamerlan Tsarnaev's former boxing coach, told ABC News that Tsarnaev was the New England champion for two or three years in a row and was considering turning pro. Curran said he had not been in contact with him since 2010.
Curran said that before the bombing he would have agreed with the portrayal of Tsarnaev as a peaceful, courteous young man.
"I would agree on all of those if I was asked two days before the bombing what I thought of this young man," Curran said. "I'd say he was a fine young man. Very good athlete. Very courteous. Just a nice guy. I'm shocked beyond belief he was involved in this."
Curran said Tamerlan Tsarnaev was an extrovert and his brother an introvert.
Sierra Schwartz said she went to Cambridge Rindge and Latin High School with Dzhokhar Tsarnaev. She recognized him immediately when she saw his photo released by authorities.
"I was like, 'Wow, that looks just like Dzhokhar,'" she said. She then noticed that his Facebook page had been deleted.
Schwartz knew he went to college, but did not remember where. She last saw him in Cambridge in the summer of 2011 before starting college. She was not aware that he had a brother.
"He was a great athlete. He did well. I think he won a scholarship for it," Schwartz said. "This is very unexpected. ... This is out of the ordinary. Completely shocking."
Schwartz is still reeling from the news that her former classmate had become the most wanted person in America.
"When I woke up, it's like I'm living a nightmare right now. It can't be described," she said earlier today.
"We all knew him for four years and that's something a lot of people can't say," she added.
The Monday bombing near the finish line of the Boston Marathon killed three people and injured more than 170.
Michael S. James contributed to this report.