Another tract downloaded included a foreword by Anwar al-Awlaki, an American propagandist for al-Qaida who was killed in a U.S. drone strike in 2011.
U.S. Attorney Carmen Ortiz of Massachusetts said Attorney General Eric Holder will decide whether to pursue the death penalty against Tsarnaev, who will be arraigned on July 10. Some of Tsarnaev's relatives have insisted he's not guilty, and his mother has said the allegations against him and his brother are lies.
The indictment assembled and confirmed details of the case that have been widely reported over the past two months and added new pieces of information.
For example, it corroborated reports that Tamerlan Tsarnaev bought 48 mortar shells from a Seabrook, N.H., fireworks store. It also disclosed that he used the Internet to order electronic components that could be used in making bombs.
The papers detail how the brothers then allegedly placed knapsacks containing shrapnel-packed bombs near the finish line of the 26.2-mile race.
The court papers also corroborated reports by authorities that Dzhokhar Tsarnaev contributed to his brother's death by accidentally running him over with a stolen vehicle during a shootout and police chase.
The charges cover the slaying of Massachusetts Institute of Technology police officer Sean Collier, who authorities said was shot in the head at close range in his cruiser by the Tsarnaevs, who tried to take his gun.
In addition, prosecutors said that during the carjacking, the Tsarnaevs forced the motorist to turn over his ATM card and his password and Dzhokhar withdrew $800 from the man's account.
At the same time the federal indictment was announced, Massachusetts authorities brought a 15-count state indictment against Dzhokhar over the MIT officer's slaying and the police shootout.
Tom Hays reported from New York.
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