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A federal grand jury returned a 30-count indictment Thursday, charging Dzhokhar Tsarnaev, a U.S. citizen who had been residing in Cambridge, Mass., with allegedly using weapons of mass destruction to kill three people at the Boston Marathon and later for his alleged role in the killing of a university police officer and the carjacking of a motorist during the getaway attempt that left Tsarnaev's older brother, Tamerlan, dead.

Dzhokhar and his brother conspired to use improvised explosive devices, the indictment charged. Tamerlan died following a gun battle with police days after the April 15 bombing, and authorities captured Dzhokhar after a massive manhunt following his escape from the same shootout. Dzhokhar was placed in a prison hospital.

Three people were killed and more than 260 wounded by the two pressure-cooker bombs that went off near the finish line of the marathon.

Tsarnaev downloaded bomb-making instructions from an Al Qaeda magazine, gathered online material on Islamic jihad and martyrdom, and later scribbled anti-American messages inside the boat where he lay wounded, the indictment said.

According to the indictment, he scrawled messages on the inside of the vessel that said, among other things, "The U.S. Government is killing our innocent civilians," "I can't stand to see such evil go unpunished," and "We Muslims are one body you hurt one you hurt us all."

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    Dzhokhar and his brother built these IEDs using pressure cookers, explosive powder, shrapnel, adhesives and other items designed to ‘shred skin, shatter bone, and cause extreme pain and suffering, as well as death,” the indictment said. These IEDs were placed at the finish line of the 117th running of the Boston marathon and detonated as onlookers cheered runners at the end of the 26.2-mile race, the indictment said.

    Three days after the bombing, the brothers were armed with five IEDs, a Ruger P95 semiautomatic handgun, ammo, a machete and a hunting knife and drove to the Massachusetts Institute of Technology’s campus, the indictment said. It was there when they fatally shot Sean Collier, a university police officer, the indictment said.

    The Tsarnaev brothers had roots in the turbulent Russian regions of Dagestan and Chechnya, which have become recruiting grounds for Islamic extremists. They had been living in the U.S. about a decade.

    The Associated Press contributed to this report.