A federal grand jury on Thursday indicted Dzhokhar Tsarnaev on murder and terrorism charges related to the Boston Marathon bombing.
The 30-count indictment charges Tsarnaev with the death of three bombing victims, the death of Massachusetts Institute of Technology police officer Sean Collier and the use of a "weapon of mass destruction."
Tsarnaev has been in federal custody since April, after being critically wounded in an hours-long armed standoff with FBI agents in the Boston area.
His older brother, Tamerlan Tsarnaev, was killed during a violent shootout with federal agents and local police days after the bombing.
The federal indictment also included details of the Tsarnaev brothers' radicalization by militant Islamic groups.
Prior to his capture, the younger Tsarnaev penned a confession, admitting the Boston bombing was in retaliation for American-led counter terrorism operations in the Mideast and elsewhere.
“The US Government is killing our innocent civilians. I can’t stand to see such evil go unpunished. We Muslims are one body, you hurt one, you hurt us all,” Tsarnaev allegedly wrote in the confession, detailed in Thursday's indictment.
"Stop killing our innocent people, we will stop," he added, according to reports in The Boston Globe.
The elder Tsarnaev reportedly downloaded reams of Islamic militant propaganda in the weeks prior to the Boston Marathon bombing, the Globe reports.
That propaganda included preachings by Anwar al-Awlaki, the U.S. citizen who U.S. intelligence officials claimed was the spiritual leader of al Qaeda's Yemen cell, known as al Qaeda in the Islamic Maghreb (AQIM).
In May, Attorney General Eric Holder admitted that al-Awlaki was one of four American citizens killed in unmanned drone strikes by American intelligence operatives.
The Boston attack spurred a furious debate in Congress on whether institutional rivalries between the FBI, Justice Department and intelligence community led to missed opportunities to prevent the bombing.
Tamerlan Tsarnaev was put on a terrorism watch list at the request of the CIA nearly a year before the deadly attack.
The agency requested Tsarnaev be placed on a watch list run by the National Counterterrorism Center after Russian intelligence contacted the CIA about a trip he took to the country in 2011.
Turf battles between the FBI, CIA and others in the intelligence community contributed to missed warnings ahead of the 9/11 attacks.
While coordination among the entities has improved over the years, it remains unclear whether interagency tensions or other factors prevented U.S. counterterrorism officials from uncovering clues that may have predicted the attack.