The two brothers suspected in the Boston Marathon bombing were described by their uncle as "losers" who were "not being able to settle themselves, and hating anyone who did."
The suspects' uncle, Ruslan Tsarni, said that his family has nothing to do with the two brothers and that he last spoke with his brother, the boys' father, a few months ago. Tsarni said he first learned of the brothers' possible involvement when reporters contacted him early this morning.
The suspects — one killed, one captured alive — are brothers of Chechen origin, at least one a legal permanent resident of the United States, law enforcement officials told NBC News.
The suspect captured alive Friday was identified as Dzhokhar Tsarnaev, 19, born in Kyrgyzstan, holding a Massachusetts driver's license and living in the Boston suburb of Cambridge. He was the suspect in the white hat in surveillance photos from the marathon released by the FBI.
(Read more: Two People in Custody in Boston Bombing Hunt)
"Of course, we're ashamed," Tsarni said. "Yes, we're ashamed. They're children of my brother who had little influence of them honestly as much as I know."
When the younger Dzhokhar was on the run, Tsarni urged him to contact authorities. He cited "being losers, not being able to settle themselves and thereby just hating everyone who did" as a possible motive for their alleged involvement.
"I say Dzhokhar, if you're alive, turn yourself in and ask for forgiveness from the victims, from the injured and from those who left," he said. "Ask forgiveness from these people."
(Read more: Photos from Boston Lock-Down)
He added that the alleged attack has nothing to do with Chechnya.
Heput a shame on the Tsarnaev family, he put a shame on the entire Chechnyan ethnicity."
The brothers' father, speaking from Russia, told The Associated Press that he is "a true angel."
An account with Dzhokhar Tsarnaev's name on a Russian social media site lists Islam as his world view, "career and money" and his personal priorities and Chechnya as an area of interest.
His brother, who was killed in a firefight with law enforcement, was identified as Tamerlan Tsarnaev, 26, born in Russia. He became a legal permanent resident in 2007, the officials said. He was the suspect in the black hat in the FBI photos.
Both men were believed to have military experience, and to have entered the country with their family in 2002 or 2003, when the family sought asylum. The nature of the military experience was not clear. Later in the morning, U.S. Army officials told NBC knows that no one matching either name had served in the active-duty Army, or the reserves.
(Read more: Scenes From the Watertown Manhunt)
The city of Cambridge awarded Dzhokhar Tsarnaev a $2,500 scholarship toward college in 2011, according to The Boston Globe. The scholarships were for students at Cambridge Rindge and Latin School, part of the Cambridge public school system.
A tense night of police activity that left a university officer dead on campus just days after the Boston Marathon bombings and amid a hunt for two suspects caused officers to converge on a neighborhood outside Boston, where residents heard gunfire and explosions.
(Read more: Terror Experts Analyze Boston Manhunt)
In 2002, Chechen militants seized a Moscow theater and held 800 people hostage for two days. Special forces raided the building and killed 41 hostage-takers; 129 hostages were killed, mostly from gas used by Russian forces.
In 2004, Chechen insurgents took hundreds of hostages in the Russian town of Beslan. The siege came to a bloody end two days later, and 330 people, about half children, were killed.
(Read more: 'Dedicated Officer' Gunned Down by Suspects)
Tamerlan Tsarnaev was killed after a chaotic chase and firefight with police early Friday. Authorities were conducting a house-to-house search in the Boston suburb of Watertown for his brother, who was considered armed and extremely dangerous. Massachusetts Gov. Deval Patrick ordered people in Boston and some suburbs to stay inside.
—By Erin McClam, Staff Writer at NBC News. CNBC's Katie Little and the Associated Press reported to this article.