By Scott Malone and Stephanie Simon
BOSTON (Reuters) - Accused Boston Marathon bomber Dzhokhar Tsarnaev was indicted by a federal grand jury on Thursday on charges of killing four people in the largest mass-casualty attack on U.S. soil since September 11, 2001.
The 30-count indictment filed in Boston federal court charges the 19-year-old ethnic Chechen with setting off two homemade pressure-cooker bombs in a crowd of thousands at the race's finish line and with committing a carjacking and engaging in a gunbattle with police before his April 19 arrest.
Tsarnaev could be executed if convicted. His public defender, Miriam Conrad, declined to comment on the charges, which include use of a weapon of mass destruction, bombing a public place and carjacking during four days that traumatized the Boston area.
"Today's charges reflect the serious and violent nature of the event ... the defendant's alleged conduct forever changed lives," said Carmen Ortiz, the U.S. Attorney in Massachusetts. She said she had met with several of the people who were wounded in the attack and relatives of those who were killed.
"We will do all that we can to pursue justice, not only on their behalf but on behalf of all of us," Ortiz said.
The April 15 bombing was followed by the shooting of a campus police officer in Cambridge, a carjacking and a late-night gunbattle with police in the nearby suburb of Watertown. Dzhokhar's 26-year-old brother Tamerlan died in the gunbattle, which led to a daylong lockdown of most of the Boston area.
That evening, Dzhokhar was found hiding in a boat in a resident's backyard and arrested after police fired a hail of bullets.
The brothers started preparing for the attack more than two months earlier, when Tamerlan traveled to a New Hampshire fireworks store to buy 48 mortar shells containing about eight pounds (3.6 kg) of explosive powder, according to the charges.
Three people died in the bomb attacks: 29-year-old restaurant manager Krystle Campbell, 23-year-old graduate student Lingzi Lu and 8-year-old Martin Richard. Days later, the pair killed a campus policeman in their attempt to escape arrest, the charges said.
The younger Tsarnaev was not present at the indictment, and Ortiz declined to comment on his condition or where he was being held. He was badly injured in the April 19 gun battle and had been held in a prison hospital west of Boston. He is scheduled to be arraigned on July 10.
Ortiz said U.S. Attorney General Eric Holder would make the final decision on whether to seek the death penalty. Legal experts said that while the large scale of the attack could motivate the government to seek the death penalty, his defense could argue that he did not fully understand his actions.
"There will be claims about his youth, about his role, the theory that it was his brother that was pulling all the strings and that this guy was a secondary mover," said Richard Broughton, an assistant professor at the University of Detroit Mercy School of Law and a former federal prosecutor.
"We haven't really had a case like this," said Karen Greenberg, director of the center on national security at Fordham Law School in New York. "Because of the lethality of this attack, it really is different from other terrorism prosecutions we've seen for a long time."
Since the World Trade Center attack in 2001, most such prosecutions have focused on failed plots, such as shoe bomber Richard Reid, who tried to blow up a plane over the Atlantic in December 2001 and is now serving a life sentence. In 2006 a jury rejected the death penalty for Zacarias Moussaoui, convicted as one of the conspirators behind the September 11, 2001 attacks.
In November, 2012, a federal judge in Massachusetts sentenced Rezwan Ferdaus to 17 years, including a decade of supervised release, after he pleaded guilty to charges stemming from a plot to a plot to fly remote-controlled planes into the U.S. Capitol building and the Pentagon. He was arrested in a sting operation after undercover agents provided him with inert explosives that he told them he planned to use.
Tamerlan Tsarnaev had been on a U.S. government database of potential terrorism suspects and Russia has twice warned the United States that he might be an Islamic militant, according to U.S. security officials.
A congressional hearing after the bombing focused on whether the FBI paid sufficient heed to Moscow, which has been in bitter conflict with Islamic militants in Chechnya and other parts of the volatile northern Caucasus region.
The Tsarnaev brothers' ethnic homeland of Chechnya, a mainly Muslim province that saw centuries of war and repression, no longer threatens to secede from Russia. But it has become a breeding ground for a form of militant Islam whose adherents have spread violence to other parts of Russia, and may have inspired the radicalization of the Boston bombers.
(Editing by Dina Kyriakidou and David Gregorio)