The accused Boston Marathon bomber Dzhokhar Tsarnaev had admitted to a role in the attack during an interrogation in hospital a day after his arrest, U.S. prosecutors said in a court filing.
That statement, and others made in the hours following Tsarnaev's arrest but before he had been informed of his rights to legal representation, should be admitted at his upcoming trial because the agents interviewing him believed there was still a risk to the public of further attacks, prosecutors said in a series of filings late Wednesday in U.S. District Court in Boston.
"From the moment the agents began questioning Tsarnaev about the Marathon bombings, he readily admitted his own involvement," prosecutors said.
While the suspect, now 20, said he and his older brother Tamerlan - who died after a gunfight with police days after the bombing attack that killed three people and injured 264 - were the only people involved in the bombing, investigators did not believe him, prosecutors said.
"Agents continued to question Tsarnaev not to extract a confession, which they already had, but because of their reasonable belief that Tsarnaev was concealing information about impending attacks, accomplices, and/or the existence of additional bombs," prosecutors said.
Tsarnaev faces the possibility of execution if convicted of the April 15, 2013 attacks, as well as the murder of an MIT police officer three days later as he and his brother attempted to flee Boston.
His lawyers earlier this month argued that the statements made while Tsarnaev was hospitalized for gunfire wounds, after police found him hiding in a drydocked boat on April 19, should not be admitted because he did not have an attorney present.
Prosecutors also released some new details of a note Tsarnaev had scrawled on the inside of that boat, in which he tried to explain his motivations. They said the note also amounted to a confession of the crime.
"Know you are fighting men who look into the barrel of your gun and see heaven, now how can you compete with that," he wrote, according to prosecutors. "We are promised victory and we will surely get it."