Accused bomber says U.S. wars fed the brothers' radicalism
Dzhokhar Tsarnaev, 19, who lay in a Boston hospital with multiple gunshot wounds, also said that he and his older brother, Tamerlan, learned how to make the pressure cooker bombs used in the attack from an al Qaida website, said the official, who spoke on condition of anonymity.
Tamerlan Tsarnaev, 26, died in a police shoot-out early Friday in which he hurled makeshift explosives at law enforcement officers before he was gunned down. He is believed to have instigated the attack that killed three people and injured more than 260 others after turning devoutly religious and possibly reading radical Islamic dogma on Internet sites or associating with radicals during visits to Russia, law enforcement officials said.
Relatives have suggested in interviews that he would have held considerable sway over his younger brother, a college student. No evidence has surfaced so far that the two Chechen brothers were influenced by a foreign terrorist organization to carry out the worst terrorist attack on U.S. soil since the suicide hijackings that toppled the World Trade Center, hit the Pentagon and crashed in a Pennsylvania field on Sept. 11, 2001.
But FBI agents have not foreclosed that possibility and will be conducting a worldwide investigation to examine the origins of their apparent radicalization, the law enforcement official said.
The FBI expects to conduct a lengthy investigation to determine for certain whether they acted alone, were assisted by other conspirators or received any assistance along the way, the official said. The investigation also will examine whether they were involved in an unsolved triple murder, apparently carried out on the 10th anniversary of the Sept. 11 terror attacks, in Waltham, Mass., the law enforcement official said. A friend of Tamerlan Tsarnaev, 25-year-old Brendan Mess, was among three young men whose throats were slit, according to The Boston Globe, which first reported the possible linkage.
The Globe reported that Tamerlan Tsarnaev had introduced Mess to the owner of a martial arts center in Allston, Mass.
The FBI disclosed last week that it received a tip from Russia in 2011 that Tamerlan Tsarnaev had been radicalized, but that the bureau's own three-month inquiry, which included an interview with him, found no evidence that he was a terrorist threat.
Republican leaders of the House Homeland Security Committee have demanded information from the FBI and intelligence agencies about what was known about Tamerlan Tsarnaev before the attack.
On Monday, a federal magistrate and public defenders joined prosecutors in Dzhokhar Tsarnaev's heavily guarded room at Beth Israel Deaconess Hospital for a brief arraignment, in which he was formally charged with the capital crime of using a weapon of mass destruction, as well as malicious destruction of property resulting in death.