Agents check Dzhokhar Tsarnaev for explosives and give him medical attention after he was caught Friday in Watertown, Mass.
WASHINGTON — With one suspect dead and the other captured and lying wounded in a hospital, the investigation into the Boston Marathon bombings turned Saturday to questions about the men’s motives and to the significance of an overseas trip one of them took last year.
Federal investigators are reviewing a visit that one of the suspected bombers made to Chechnya and Dagestan, predominantly Muslim republics in the north Caucasus region of Russia. Both areas have active militant movements.
There are concerns in Congress about the FBI’s handling of a request from Russia before the trip to examine possible links to extremist groups in the region.
Tamerlan Tsarnaev, who died early Friday after a shootout with police, spent six months of last year in Dagestan.
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Tamerlan’s father, Anzor, said his son had returned to renew his passport, but his stay was prolonged and, analysts said, may have marked a step toward the bombing of the Boston Marathon.
Investigators began scrutinizing events before the fatal attack as Boston began to feel like itself for the first time in nearly a week. Monday had brought the bombing, near the finish line of the Boston Marathon, which killed three and wounded more than 180. Friday’s lockdown of the entire region culminated several tense days as police searched for the younger brother from suburban backyards to an Amtrak train bound for New York City.
The motivations of Tamerlan Tsarnaev, and his younger brother, Dzhokhar, are not publicly known. Dzhokhar, 19, was too wounded to speak Saturday, Massachusetts Gov. Deval Patrick said. Counterterrorism agents trained in interrogating high-value detainees were waiting to question him.
Concerns arose about the Obama Administration’s decision to question him for a period without giving him a Miranda warning, under an exception for questions about immediate threats to public safety.
Of Chechen heritage, the Tsarnaev brothers lived in the United States for years. No direct ties have been established with known Chechen terrorist or separatist groups.
The significance of Tamerlan’s trip to Dagestan was magnified late Friday when the FBI disclosed in a statement that in 2011 “a foreign government” — now acknowledged by officials to be Russia — asked for information about Tamerlan.
The FBI indicated that the request was “based on information that he was a follower of radical Islam and a strong believer, and that he had changed drastically since 2010 as he prepared to leave the United States for travel to the country’s region to join unspecified underground groups.”
The senior law enforcement official said the Russians feared he could be a risk, and “they had something on him and were concerned about him, and him traveling to their region.”
But the FBI did not follow up on Tamerlan Tsarnaev once he returned, law enforcement acknowledged Saturday, adding that the bureau had not kept tabs on him until he was identified Friday as the first suspect in the marathon bombing.
The FBI responded to Russia’s request by checking “U.S. government databases and other information to look for such things as derogatory telephone communications, possible use of online sites associated with the promotion of radical activity, associations with other persons of interest, travel history and plans, and education history,” the statement explained.
In January, 2011, two agents from the bureau’s Boston office interviewed Tamerlan and relatives, a law enforcement official said Saturday.
“The FBI did not find any terrorism activity, domestic or foreign,” and conveyed those findings to “the foreign government” by the summer of 2011, the FBI said.
As the law enforcement official put it, “We didn’t find anything on him that was derogatory.”
The Russian state news agency RIA Novosti quoted the father of the Tsarnaev brothers recalling the FBI’s questioning of his elder son, “two or three times.” He said they had told his son that the questioning “is prophylactic, so that no one sets off bombs on the streets of Boston, so that our children could peacefully go to school.”
One month after Tamerlan returned to the United States, a YouTube page appearing to be his was created and featured multiple jihadi videos that he had endorsed.
Federal prosecutors were drafting a criminal complaint against Dzhokhar Tsarnaev, who was wounded in the leg and neck and had lost a great deal of blood when he was captured Friday evening.
An official said the criminal complaint would likely include charges stemming from both the bombings and the shooting, possibly including the use of weapons of mass destruction, an applicable charge for the detonation of a bomb. That charge, the official said, carries a maximum penalty of death. While Massachusetts has outlawed the death penalty, federal law allows it.