Attorney General Eric Holder said the Justice Department will seek the death penalty in the case of Dzhokhar Tsarnaev, the man charged in connection with the bombing of the 2013 Boston Marathon.
"The nature of the conduct at issue and the resultant harm compel this decision," Holder said in a statement.
As we've reported, the 20-year-old Tsarnaev has been charged with 30 counts, including killing four people and using weapons of mass destruction.
The twin bombs on April 15, 2013, also injured more than 250 people.
In a notice filed with a federal court in Massachusetts on Thursday, prosecutors argued that Tsarnaev intentionally killed three people at the marathon, including a "vulnerable" 8-year-old Martin Richard, and then killed a campus police officer while trying to evade capture.
Tsarnaev, prosecutors argue, acted in a "heinous, cruel and depraved manner" with "substantial planning and premeditation."
"Tsarnaev received asylum from the United States; obtained citizenship and enjoyed the freedoms of a United States citizen; and then betrayed his allegiance to the United States by killing and maiming people in the United States," the prosecutors write.
Tsarnaev, prosecutors also charge, "demonstrated a lack of remorse."
U.S. Attorney Carmen Ortiz, who is handling the case, said the "process by which this decision was made is confidential," so she could not comment further.
"The case will now continue to proceed through the pretrial process and the next scheduled court event is a status conference set for February 12, 2014," Ortiz said in a statement.
NPR's Tovia Smith tells our Newscast unit that Massachusetts doesn't have the death penalty for state crimes and "federal prosecutors have sought the death penalty here only twice in recent decades."
Before the announcement, Tovia spoke to Liz Norden, whose two sons each lost a leg in the attack.
"Is [the death penalty] justice?" she said. "I don't know if it would be justice, but I think it would be proper that all options are [available to] jurors."
Update at 2:57 p.m. ET. He'll 'Die In Prison':
Massachusetts Gov. Deval Patrick issued this statement:
"One way or another, based on the evidence, Tsarnaev will die in prison. In each milestone of this case today's announcement, the trial and every other significant step in the justice process the people hurt by the Marathon bombings and the rest of us so shocked by it will relive that tragedy. The best we can do is remind each other that we are a stronger Commonwealth than ever, and that nothing can break that spirit."