WASHINGTON -- The two men suspected in the Boston Marathon bombings were armed with a small arsenal of guns, ammunition and explosives when they first confronted police early Friday, and were most likely planning more attacks, the authorities said Sunday.
U.S. officials said they were increasingly certain that the two suspects had acted on their own, but were looking for any hints that someone had trained or inspired them. The FBI is broadening its global investigation in search of a motive and pressing the Russian government for more details about a Russian request to the FBI in 2011 about one of the suspects' possible links to extremist groups, a senior U.S. official said Sunday.
New details about the suspects, their alleged plot and the widening inquiry emerged Sunday, including the types of weapons that were used and the bomb design's link to a terrorist manual. Lawmakers also accused the FBI of an intelligence failure, questioning whether the agency had responded forcefully enough to Russia's warnings.
The surviving suspect, Dzhokhar Tsarnaev, 19, remained in a Boston hospital in serious condition. The authorities said they believed that he had tried to kill himself, because a gunshot wound to his neck "had the appearance of a close-range, self-inflicted style," the senior U.S. official said.
As investigators intensified their search for clues, the investigation's focus shifted in the past two days from a manhunt that relied heavily on cutting-edge surveillance technology to help track down the suspects to more traditional investigative methods such as interviews with friends, relatives and others who knew the suspects and examinations of computers, phones, writings and their possessions.
More details of what the authorities said was the original plot were becoming clearer. Boston police commissioner Edward Davis said the authorities believed that Mr. Tsarnaev and his older brother, Tamerlan, 26, had planned more attacks beyond the April 15 bombings at the finish line of the Boston Marathon, which killed three people and injured more than 170. When the suspects seized a Mercedes-Benz sport utility vehicle and held the driver hostage, they told him that they planned to head to New York City, the senior U.S. official said Sunday.
It was not clear whether the suspects had told the driver what they planned to do there.
Mr. Davis told CBS News' "Face the Nation" on Sunday: "We have reason to believe, based upon the evidence that was found at that scene -- the explosions, the explosive ordnance that was unexploded and the firepower that they had -- that they were going to attack other individuals."
Along with determining that the suspects had made at least five pipe bombs, the authorities recovered four firearms that they believe the suspects used, according to a law enforcement official. The authorities found an M-4 carbine rifle -- a weapon similar to ones used by U.S. forces in Afghanistan -- on the boat where the younger suspect was found Friday night in Watertown, Mass., a city 10 miles west of Boston.
Two handguns and a BB gun that the authorities believe the brothers used in an earlier shootout with officers in Watertown were also recovered, said one official briefed on the investigation. The authorities said they believe the suspects had fired roughly 80 rounds in that shootout, in which Tamerlan Tsarnaev was fatally wounded, the official said.
One main unanswered question is whether others helped plan and carry out the Boston Marathon attack, which federal officials said was still under investigation. Boston Mayor Thomas Menino said he believed the brothers were not affiliated with a larger network.
"All of the information that I have, they acted alone, these two individuals, the brothers," he said on ABC News' "This Week."
Some investigators said they believe the suspects used a design for the pressure-cooker bombs that they allegedly detonated from a manual published in the online English-language magazine of al-Qaida's affiliate in Yemen. Mr. Menino said Tamerlan Tsarnaev had "brainwashed" his younger brother to follow him and "read those magazines that were published on how to create bombs, how to disrupt the general public, and things like that."
The suspects' uncle, Ruslan Tsarni, who lives in Maryland, said in an interview Sunday that he had first noticed a change in the older brother in 2009. Mr. Tsarni sought advice from a family friend, who told him that Tamerlan Tsarnaev's radicalization had begun after he met a recent convert to Islam in the Boston area. Mr. Tsarni said he had later learned from a relative that his nephew had met the convert in 2007.
As scrutiny increased on the how the brothers had been radicalized, Rep. Michael McCaul, R-Texas, who heads the Homeland Security Committee, and Rep. Peter King, R-N.Y., who is also on the panel, sent a letter to the directors of three of the nation's leading intelligence-gathering agencies calling the FBI's handling of the case "an intelligence failure."
They said Tamerlan Tsarnaev was the fifth man since the Sept. 11, 2001, attacks to be suspected of committing terrorism while under investigation by the bureau. Agents had questioned him in 2011 in response to a request from the Russian government, a year before he traveled to Chechnya and Dagestan, predominantly Muslim republics in the North Caucasus region of Russia. Both have been hotbeds of militant separatists.
The request from the Russian government was directed to the FBI's legal attache at the U.S. Embassy in Moscow in January 2011, a senior U.S. official said. The Russians feared Tamerlan Tsarnaev could be a risk, and said their 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 FBI said in a statement Friday.
A senior U.S. official said Sunday that despite requests from U.S. officials for more details at the time, this was all the information the Russians provided.
The FBI responded 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," it said in the statement.
The bureau then sent two counterterrorism agents from its Boston field office to interview Tamerlan Tsarnaev and family members, a senior U.S. official said Saturday.
According to the FBI's statement, "The FBI did not find any terrorism activity, domestic or foreign," and conveyed those findings to "the foreign government" -- which officials say was Russia -- by the summer of 2011.
On "State of the Union," Sen. Lindsey Graham, R-S.C., said: "The fact that we could not track him has to be fixed. It's people like this that you don't want to let out of your sight, and this was a mistake. I don't know if our laws are insufficient or the FBI failed, but we're at war with radical Islamists, and we need to up our game."
In the wake of the current furor, the FBI has pressed Russian authorities for more details about Moscow's original request on Tamerlan Tsarnaev, as well as any information the Russian intelligence services have developed since then, according to a senior U.S. official.
These discussions are "sensitive," the official said, because of the differences in protocol and laws between the two countries, and the Russians' reluctance to disclose confidential intelligence to foreign governments.
Tensions also escalated Sunday over how to handle the case of the surviving suspect. Republican lawmakers want President Barack Obama to declare Dzhokhar Tsarnaev an "enemy combatant" in order to question him without a lawyer and other protections of the criminal justice system.
But the administration is pushing back. Dzhokhar Tsarnaev, a naturalized U.S. citizen, is a Muslim, but there is as yet no known evidence suggesting that he is part of al-Qaida; the United States is engaged in an armed conflict with al-Qaida, not all Muslim extremists.
First Published April 22, 2013 4:00 AM