The Department of Justice said Thursday that it will seek the death penalty for Dzhokhar Tsarnaev, the alleged Boston Marathon bomber, citing the “heinous, cruel and depraved manner” of the attack that killed three people, injured more than 260, and sent a wave of shock and fear into the region.
Noting that Tsarnaev has shown no remorse, federal prosecutors said they would seek the death penalty because of his “betrayal of the United States’’ and his decision to target the Boston Marathon, “an iconic event that draws large crowds of men, women, and children to its final stretch, making it especially susceptible to the act and effects of terrorism.”
US Attorney General Eric Holder authorized federal prosecutors to seek capital punishment if Tsarnaev is convicted, saying, “The nature of the conduct at issue and the resultant harm compel this decision.”
The US attorney in Boston, Carmen M. Ortiz, whose office is prosecuting the case, said, “We support this decision, and the trial team is prepared to move forward with the prosecution.”
Miriam Conrad, the head public defender in Massachusetts and one of Tsarnaev’s lawyers, said the defense team had no comment.
One of the people injured in the April 15 bombings, Jarrod Clowery, a 36-year-old carpenter from Millville, said he had no emotional reaction to the decision, saying that Tsarnaev and his brother, Tamerlan, an alleged coconspirator, “were tried and convicted by a power higher than us the moment they did what they did.”
“I’m moving on with my life. . . . It has no bearing on my life whatsoever,” said Clowery, whose legs were badly burned and struck by shrapnel.
Massachusetts state courts do not permit capital punishment, but Tsarnaev could be sentenced to death because he faces the charges in a federal case. An execution, however, would have to take place in a state that allows the death penalty. Just three defendants have been executed under the federal death penalty since 1988.
In capital punishment cases, prosecutors are required to announce from the outset whether they will seek the death penalty, and US District Court George A. O’Toole Jr. had given prosecutors until Friday to decide, calling it a “significant event in the life of the case.”
With the authorization, the US attorney’s office can now request a trial date. The threat of a death sentence can also now be a factor in any plea negotiations.
Tsarnaev’s defense team may also consider whether to ask the judge to relocate the trial to a different district, either in state or out of state.
Tsarnaev, now 20, faces 30 charges in a federal indictment in connection with the bombing that plunged the region into terror for five days, until his arrest after a police chase and firefight in Watertown. Tamerlan Tsarnaev was killed during the confrontation in Watertown.
Krystle Campbell, 29; Lingzi Lu, 23; and Martin Richard, 8, died in the blasts. Dzhokhar Tsarnaev also faces charges in the fatal shooting of MIT police Officer Sean Collier.
Of the 30 counts Tsarnaev faces, prosecutors say they will justify the death sentence for 17 of them by proving several necessary factors, including that the killings and injuries were intentional, that Tsarnaev willingly took part in the acts that resulted in death, and that he knew they could end in death.
In the document notifying the courts they would seek the death penalty, prosecutors also cited several arguments that they were not required to make by law, including Tsarnaev’s selection of the Marathon as the site of the bombings .
Tsarnaev, who was born in Kyrgyzstan and later became a US citizen, “enjoyed the freedoms of a United States citizen [then] betrayed his allegiance to the United States by killing and maiming people in the United States,” prosecutors said.
If he is convicted, prosecutors would have to argue for the death penalty before a jury in a separate sentencing trial. Assistant US Attorney William D. Weinreb said in a previous hearing that a trial could last three months and that the sentencing trial could last an additional two months.
Holder’s decision means that the federal court system in Massachusetts will have two pending death penalty cases. The US is also seeking capital punishment for Gary Lee Sampson, an admitted serial killer.
A federal jury agreed to issue the death sentence for Sampson in 2003, but a federal judge vacated that decision in 2011, after finding that one of the jurors withheld information. Prosecutors are seeking the death penalty in a new trial.
Since federal death penalty laws were first enacted in 1988, federal prosecutors have sought the death penalty two other times in Massachusetts.
In the case of two Dorchester gang members a decade ago, the prosecutors ultimately dropped the charges, and the men were tried in state court.
For Kirsten Gilbert, a former nurse who was convicted in 2001 of administering lethal injections to patients, a jury chose a life sentence, rather than the death penalty.
Since 1988, the US attorney general has authorized the death penalty for 492 defendants.
Opponents of the death penalty — the Boston Bar Association declared its opposition to capital punishment earlier this month — assert that it provides an “illusion of ultimate punishment.” Holder has previously said that he personally opposes capital punishment.
A Globe poll in September showed that 57 percent of Massachusetts respondents supported a life sentence for Tsarnaev, compared with 33 percent who favored the death penalty.
David P. Hoose, a Northhampton-based lawyer who handles death penalty cases, said that while the federal government has authorized fewer capital cases in recent years, he expected it would seek the death penalty in Tsarnaev’s case, noting the overall nature of the terrorist attack.
“If they ever want to maintain any credibility that there is a federal death penalty and they’re going to use it, of course, they’re going to authorize it in this case,” he said. “They’re not ready to declare a de facto moratorium on the death penalty. If they didn’t approve this one, that’s what they’d be doing.”
Holder’s decision drew a quick reaction from elected and law enforcement officials, civil liberties groups, victims, and people who provided aid to those who were injured.
Carol Rose, executive director of the American Civil Liberties Union of Massachusetts, said that the union opposes the death penalty “because it is discriminatory and arbitrary and inherently violates the constitutional ban against cruel and unusual punishment.”
Former Boston police commissioner Edward F. Davis, who led the department during the attacks, said that he supports the decision and that he was not surprised, given the strength of the evidence. A jury should decide, he said, and Tsarnaev should not be able to avoid the death penalty by pleading guilty.
Mayor Martin J. Walsh of Boston said he opposed the death penalty as a state representative, but that he supported the process Holder followed in making the decision.
Governor Deval Patrick said that the decision and other milestones in the case force people affected by the bombings to relive the tragedy, and added, “One way or another, based on the evidence, Tsarnaev will die in prison.”
Maria Cramer and Meghan Irons of the Globe staff contributed to this report. Valencia can be reached at MValencia@globe.com.