Investigators were seeking a motive for the Boston Marathon bombings and whether others were involved as they awaited a chance yesterday to interview the surviving ethnic Chechen suspect.
Dzhokhar Tsarnaev, 19, was in a Boston hospital seriously wounded and unable to speak, after he was captured late on Friday at the end of a huge manhunt.
His brother, Tamerlan Tsarnaev, 26, was killed in a firefight with police earlier on Friday.
Investigators are trying to determine if others had a role in detonating bombs made in pressure cookers and packed with ball bearings and nails that exploded at the Boston Marathon on Monday last week, killing three people and injuring 176.
Tamerlan traveled to Moscow in January last year and spent six months in the region, a law enforcement source said. However, it was unclear what he did while he was there and if he could have had contact with militant Islamist groups in Russia’s Caucasus region.
Authorities have yet to charge Dzhokhar, who will be defended by the US Federal Public Defender Office that represents criminal suspects who cannot afford a lawyer.
Sources had said he would face charges on Saturday, but late in the evening officials from the US Attorneys’ Office and the US Department of Justice indicated no statement would be made before yesterday.
The role of the FBI is also being questioned after the agency said it had interviewed Tamerlan in 2011 after Russian security services raised concerns he followed radical Islam. The FBI said it did not find any “terrorism activity” at that time.
However, the brothers’ mother, Zubeidat Tsarnaeva told a Russian TV station that Tamerlan had been under FBI surveillance for years.
The New York Times, citing unnamed federal officials, reported authorities had held up Tamerlan’s application for US citizenship because of the FBI’s 2011 interview.
Records show Tamerlan was arrested when police were called to a report of domestic violence in 2009.
Dzhokhar, a student at the University of Massachusetts Dartmouth, was shot in the throat and could not speak, a source said.
“We have a million questions and those questions need to be answered,” Massachusetts Governor Deval Patrick said on Saturday.