BOSTON // Prosecutors charged Dzhokhar Tsarnaev on Monday with carrying out last week's bomb attacks on the Boston Marathon that killed three people and injured more than 200, US officials said.
The formal charge, which could carry the death penalty if the 19-year-old Tsarnaev is convicted, was overseen by a magistrate judge at Boston's Beth Israel Deaconess Hospital, a court official said.
Tsarnaev was being treated there, listed in serious condition. The criminal complaint against him said he suffered gunshot wounds to his head, neck, legs and hand during shoot-outs with police hunting him down last week.
"Although our investigation is ongoing, today's charges bring a successful end to a tragic week for the city of Boston, and for our country," US attorney general Eric Holder said in a statement.
Two bombs made from pressure cookers and left in backpacks ripped through the crowded finish line of the famous Boston Marathon road race a week ago.
Tsarnaev was captured last Friday after a manhunt in which his older brother and suspected accomplice, 26-year-old Tamerlan Tsarnaev, was killed.
Dzhokhar Tsarnaev was charged with using a weapon of mass destruction and malicious destruction of property resulting in death. If convicted, he could be sentenced to death, life in prison, or a term of any number of years, the US Justice Department said.
Tsarnaev, an ethnic Chechen college student, was unable to speak due to his injuries. But the fact he was charged on Monday meant that he was communicative, because the magistrate judge would have to be satisfied he was aware of the proceedings.
Police previously declined to comment on media reports he was communicating with authorities in writing.
Also on Monday, White House spokesman Jay Carney ruled out treating Tsarnaev, a naturalised US citizen, as an enemy combatant in the legal process.
"We will prosecute this terrorist through our civilian system of justice. Under US law, United States citizens cannot be tried in military commissions," Carnet told a news briefing.
Tsarnaev's capture on Friday night capped a week of blasts, shootouts, lockdowns and one of the largest manhunts in US history.
The criminal complaint described a detailed sequence of events around the bombings, based on video and still photographs, some from building security cameras.
An FBI agent whose affidavit was used in the complaint, said the brothers were seen walking in Boylston Street near the marathon finish line 11 minutes before the explosions, each wearing a backpack.
At one point, the older Tsarnaev headed closer to the finish line and the location of what would be the first explosion, the complaint said. His brother, meanwhile, headed for a sidewalk in front of a restaurant, near where the second explosion would occur.
Thirty seconds before the first explosion, the younger brother started fidgeting with his cell phone. After the first blast, virtually everyone around him turned to look in that direction "in apparent bewilderment and alarm," while Dzhokhar Tsarnaev appeared calm, the complaint said.
He walked away from the finish line, having left his backpack on the ground where he had been standing, the complaint said. About 10 seconds later the second explosion ripped through the crowd.
A grand jury could still charge Tsarnaev with more crimes, said former federal prosecutor and University of Notre Dame law professor Jimmy Gurulé.
"These are preliminary charges and I think the full charges will follow after there's been a presentment to a federal grand jury," Gurulé said.
A week after the bombings, the crime scene around the blasts was still closed but was expected to reopen within a day or two. Signs declaring "Boston Strong" hung about the city.
Memorial services were set on Monday for two of those killed in the bombings: Krystle Campbell, a 29-year-old restaurant manager, and Chinese graduate student Lingzi Lu. An 8-year-old boy, Martin Richard, was also killed.
Ten of the injured lost limbs.
The city also paused at 2.50pm (1850 GMT) to mark the moment a week ago when the two bombs exploded.
Police said the Tsarnaev brothers made enough additional bombs for them to believe that more attacks were planned.
The Tsarnaev brothers emigrated to the United States a decade ago from Dagestan, a predominantly Muslim region in Russia's Caucasus. Their parents, who moved back to southern Russia some time ago, have said their sons were framed.
Much of investigators' attention has focused on a trip to Russia last year by Tamerlan Tsarnaev, and whether he became involved with or was influenced by Chechen separatists or Islamist extremists there.
That trip, combined with Russian interest in Tamerlan communicated to US authorities and an FBI interview of him in 2011, have raised questions whether danger signals were missed.