Story highlights Dzhokhar Tsarnaev contributed to his brother's death, indictment says

Counts involve alleged use of weapons of mass destruction and killing of MIT officer

Indictment: IEDs were made from pressure cookers, explosive powder, shrapnel, other items

An arraignment is set for July 10 in U.S. District Court

A federal grand jury has returned a 30-count indictment against Dzhokhar Tsarnaev, the surviving suspect in the Boston Marathon bombings, that alleges he used a weapon of mass destruction.

Tsarnaev is charged with killing four people -- three spectators who died in the bombings and a Massachusetts Institute of Technology police officer ambushed in his cruiser a few days later -- and "maiming, burning and wounding scores of others," U.S. Attorney Carmen Ortiz said.

"I have met several of those that were injured on April 15, as well as members of the deceased's families," Ortiz said. "Their strength is extraordinary, and we will do everything we can to pursue justice, not only on their behalf but on behalf of all of us."

At least 264 people were wounded in the double bombings, which took place near the marathon finish line.

JUST WATCHED Analysis: Dzhokhar not hapless brother Replay More Videos ... MUST WATCH Analysis: Dzhokhar not hapless brother 03:08

JUST WATCHED Tsarnaev indicted on 30 counts Replay More Videos ... MUST WATCH Tsarnaev indicted on 30 counts 01:52

JUST WATCHED McCaul: Suspect's mom exploiting tragedy Replay More Videos ... MUST WATCH McCaul: Suspect's mom exploiting tragedy 04:42

JUST WATCHED Dzhokhar Tsarnaev in his own words Replay More Videos ... MUST WATCH Dzhokhar Tsarnaev in his own words 02:23

The grand jury charged Dzhokhar Tsarnaev with the 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, and aiding and abetting.

The indictment details the planning that allegedly went into the attacks. It says that, on February 6, Tamerlan Tsarnaev bought 48 mortars containing about eight pounds of explosive powder from a fireworks store in Seabrook, New Hampshire.

It also says that Dzhokhar Tsarnaev, 19, downloaded a copy of Inspire magazine, which included instructions on building IEDs using pressure cookers and explosive powder from fireworks.

Three days after the attacks, on April 18, the FBI released photographs of the brothers, identifying them as bombing suspects.

Hours later, they drove their Honda Civic to the MIT campus, where they shot and killed officer Sean Collier and attempted to steal his service weapon, the indictment says. They were allegedly armed with five IEDs, a Ruger P95 semiautomatic handgun, ammunition, a machete and a hunting knife.

The indictment alleges that late that night, the brothers carjacked a Mercedes in Boston by pointing a gun at a man -- identified in the document as D.M. -- and threatening to kill him.

They then allegedly drove the man to an automatic teller machine, where they forced him to withdraw $800.

About 12:15 a.m. on April 19, D.M escaped the car and called 911.

Soon after, police discovered the Tsarnaevs at an intersection in nearby Watertown, where they tried to apprehend them, but the brothers fired at the police and used four IEDs against them, the 74-page indictment alleges.

At about 12:50 a.m., police tackled the elder brother and were trying to handcuff him when Dzhokhar Tsarnaev got back into the Mercedes and drove it at the officers, according to the indictment. He wound up running over his brother, "seriously injuring him and contributing to his death," and causing "serious bodily injury" to a Massachusetts Bay Transportation Authority officer.

The younger Tsarnaev escaped, abandoned the car nearby and hid in a drydocked boat in the backyard of a home in Watertown until he was captured by police, the indictment says.

While he was hiding in the boat, he scrawled messages on an inside wall and boat beams that give a hint about his alleged motivation, according to the indictment.

The indictment says messages included: "The U.S. Government is killing our innocent civilians." "I can't stand to see such evil 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."

Seventeen of the charges authorize a penalty of up to life in prison or the death penalty. The other charges authorize a maximum penalty of life in prison or a fixed term of years. Tsarnaev is scheduled to be arraigned on July 10 in U.S. District Court in Boston.

The case will be handled by Judge George A. O'Toole Jr., who was assigned the case at random, the federal court in Boston announced Thursday. O'Toole received his law degree from Harvard Law School in 1972 and was nominated to the district court in 1995 by President Bill Clinton.

Alleged conspiracy started no later than February

The indictment alleges that the brothers conspired to use improvised explosive devices against people, property and public places from no later than February until Dzhokhar Tsarnaev was apprehended.

"The brothers placed IEDs among the crowds of spectators who were cheering the runners towards the Marathon finish line" and "detonated the bombs seconds apart, killing three people, maiming and injuring many more, and forcing a premature end to the Marathon."

The IEDs were made from pressure cookers, explosive powder, shrapnel, adhesives and other items, and were designed to shred skin, shatter bone and cause extreme pain and suffering, as well as death, the indictment said.