A federal grand jury on Thursday issued a 30-count indictment against accused Boston Marathon bomber Dzhokhar Tsarnaev ahead of his July 10 arraignment in the District of Massachusetts. A state Superior Court grand jury issued a separate 15-count indictment.

In the federal case, Tsarnaev was indicted for allegedly planting two bombs near the marathon's finish line on April 15 that killed three people and injured more than 260.

He’s also charged with murdering Massachusetts Institute of Technology police officer Sean Collier while on the run on April 18.

Tsarnaev, 19, allegedly carried out the bombings with his brother, Tamerlan, 26, who was fatally wounded during an early morning shootout with police. A transit police officer was seriously wounded during that gunplay in Watertown, Mass.

During a press conference, Suffolk County, Mass., District Attorney Daniel Conley, who could have pressed state charges for bombings, said that, “given the facts and circumstances and the many federal statutes available,” the most effective avenue was to prosecute Dzhokhar Tsarnaev in federal court.

Conley likened the situation to the 1995 bombing of the federal building in Oklahoma City by Timothy McVeigh and Terry Nichols, who were tried in federal court (although Nichols was later tried on related charges in state court).

The court filing provided clues about the motive. It said that Dzhokhar was captured on the evening of April 19, after hiding for several hours in a dry docked boat.

He wrote several messages inside the boat, including: “The U.S. 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;” “Now I don’t like killing innocent people it is forbidden in Islam but due to said [unintelligible] it is allowed;” and “Stop killing our innocent people and we will stop.”

The indictment said that the Tsarnaev brothers took several steps to prepare for the bombings. Dzhokhar downloaded a digital copy of three publications promoting violent jihad against those who threaten Islam, it said. He also downloaded a copy of Inspire magazine, reportedly published by al-Queda in the Arabian Penninsula, which includes information about how to build improvised explosive devices using pressure cookers or other materials. The Boston bombs were made with pressure cookers.

The indictment claimed that the two brothers went to New Hampshire for target practice with 9mm handguns on March 20, and that Dzhokhar opened a prepaid cellphone account on April 14 under the name Jahar Tsarni and used that same phone during the bombings the next day.

The document detailed two steps undertaken by Tamerlan—a February trip to a New Hampshire fireworks shop to buy mortars that contained about eight pounds of low explosive powder; and the April 5 purchase of electronic components that could be used to make improvised explosive devices.

The federal charges include:

* Use of a weapon of mass destruction resulting in death and conspiracy.

· Bombing of a place of public use resulting in death and conspiracy.

· Malicious destruction of property resulting in death and conspiracy.

· Use of a firearm during and in relation to a crime of violence.

· Use of a firearm during and in relation to a crime of violence causing death.

· Carjacking resulting in serious bodily injury.

· Interference with commerce by threats or violence.

· Aiding and abetting.

Seventeen of the charges carry either the death penalty or the possibility of life in prison. The remaining charges have a maximum penalty of life in prison or a fixed term of years.

Federal public defender for the District of Massachusetts Miriam Conrad declined to comment. She is defending Tsarnaev with assistants Timothy Watkins and William Fick with the help of Judy Clarke of San Diego's Clarke & Rice.

Clarke did not respond to calls for comment.

The state criminal charges include:

· Murder.

· Attempted armed robbery.

· Four counts of armed assault with intent to murder.

· Four counts of assault with a dangerous weapon.

· Kidnapping.

· Armed robbery.

· Unlawful possession of a firearm.

· Possession of a large capacity feeding device.

· Possession of a firearm with a defaced serial number.

Sheri Qualters can be contacted at squalters@alm.com.