* Russians contacted U.S. twice about Tsarnaev -sources
* Family of suspects cites man named "Misha" as influence
* Suspect's name was on U.S. counterterrorism list
U.S. intelligence was alerted when one of the Boston bombing suspects traveled to a volatile region of Russia last year, U.S. officials said on Wednesday, raising new questions about the government's handling of the case and how well law enforcement agencies share information and cooperate with one another.
The trip by the suspect, Tamerlan Tsarnaev, to southern Russia has come under scrutiny over whether he became involved with or was influenced by Chechen separatists or Islamic militants there, according to U.S. officials who spoke on condition of anonymity.
Russia, which tipped off the FBI in early 2011 with concerns that Tsarnaev may have been a radical Islamist, made a second, identical request to the CIA in late September of the same year, they said. The FBI interviewed Tsarnaev following the first tip and found no serious threat.
Police say the ethnic Chechen brothers Tamerlan and Dzhokhar Tsarnaev planted and detonated two pressure-cooker bombs near the finish line of the Boston Marathon on April 15, killing three people and injuring 264.
Tamerlan Tsarnaev, 26, was killed in a shootout with police four days later, and Dzhokhar Tsarnaev, 19, was wounded and captured. He is hospitalized in fair condition and charged with two crimes that carry the possibility of the death penalty.
The disclosure of the second warning from the Russians raised questions about whether the CIA and the FBI failed to share the information, even after reforms enacted to prevent information-hoarding following the Sept. 11, 2001, hijacked plane attacks.
"That's something that we have to look at," said Senator Dan Coats, a Republican from Indiana and member of the Senate Intelligence Committee. "That's one of the key things that we have learned and need to work on to make sure it doesn't happen again, and that is simultaneous communication to all the relevant agencies when a warning is posted."
The two bombs in Boston were detonated with the kind of remote device used to control a toy car, U.S. investigators said in a briefing to a House of Representatives panel on Wednesday.
The briefing by the FBI and the Department of Homeland Security to the House Intelligence Committee revealed that the two brothers apparently became radicalized by anti-U.S. information on the Internet, members of Congress said.
"It looks like they built their bomb based on Inspire magazine and the article said how to build a bomb in mom's kitchen," said Representative Dutch Ruppersberger of Maryland, the top Democrat on the House Intelligence Committee.
The online magazine Inspire, circulated by Yemen-based al Qaeda in the Arabian Peninsula, publishes English-language exhortations to would-be Western jihadists to carry out attacks with whatever means they have at hand. It recently published detailed instructions on how to build homemade devices.
"The younger bomber in whatever type of communication he's using said that's where they got the instruction to build the bomb," Ruppersberger said.
NEW KIND OF THREAT
Authorities say attention has focused on the elder brother as the driving force behind the bombings. As part of the FBI's probe in 2011, his name had been entered into a U.S. Customs and Border Protection database known as TECS.
U.S. officials said that when he left the United States for a six-month stay in Russia in January 2012, the TECS database sent an alert to the Joint Terrorism Task Force, a multi-agency FBI-led body in Boston.
It remains unclear what investigators did with the information.
Ruppersberger said the FBI went back to the Russians repeatedly seeking more information but got no response.
"They followed through the protocols that were necessary once they got that information, but then they got no other information from the Russians," he said.
Adam Schiff, a California Democrat on the House committee, said he felt the inquiries from the Russians "were appropriately followed up upon."
"Our agencies get thousands and thousands of leads like we did from the Russians," he said, noting that some are efforts by foreign governments to go after political dissidents.
Schiff said the Boston bombings posed a new kind of threat to the United States, "where we're now facing more what Europe has faced, with an alienation of part of the immigration population and self-radicalization.
"That's a different challenge than those that are trained overseas or receive material support from overseas and come here to attack us, and I think that will cause us to do some things differently," he said.
WHO IS MISHA?
The briefing indicated that some of the elder brother's dissatisfaction may have stemmed from the U.S. wars in Iraq and Afghanistan, Ruppersberger said.
A man who said he was the brothers' uncle, Ruslan Tsarni, said a man he knew only as Misha had influenced Tamerlan Tsarnaev's deepening interest in Islam.
Standing at the door of his home in Montgomery Village, Maryland, Tsarni said he first heard of Misha, whom he described as of Armenian descent, in 2009.
Misha was "working with Tamerlan, pulling him into Islam, introducing him into Islam in such a way that the guy in a short time quit what he was doing," he said. "He quit boxing, he quit music."
"It seems like, what we heard, Tamerlan had been quite occupied with him," Tsarni said.
Dzhokhar Tsarnaev has told investigators that he and his brother acted without assistance from any foreign or domestic militant groups, according to members of Congress briefed by law enforcement.
"That basically seems to be the story, but I don't see how we can accept that," Representative Peter King, a New York Republican on the Homeland Security Committee, told CNN.
"It may end up being the truth but ... I don't see why he would be giving up any accomplices he may have or talking about any connections his brother may have had in Chechnya or Russia," King said on Wednesday.
Vice President Joe Biden and law enforcement agents from around the United States attended a memorial at the Massachusetts Institute of Technology for a university police officer who authorities say was shot dead by the Tsarnaev brothers on Thursday night.
Sean Collier, 26, was killed about five hours after the FBI released pictures of the two suspects, asking for the public's help in tracking them down.
Biden called the prestigious university a symbol of what Islamic extremists oppose.
"You are their worst nightmare," Biden said. "All of these things these perverted jihadis, self-made or organized, all the things they fear."