BOSTON - The surviving suspect in the Boston Marathon bombings acknowledged to the FBI his role in the attacks but did so before he was advised of his constitutional rights to keep quiet and seek a lawyer, officials said Wednesday.
It is unclear whether those statements would be admissible in a criminal trial and, if not, whether prosecutors even need them to win a conviction.
Officials said physical evidence, including a 9 mm handgun and pieces of a remote-control device commonly used in toys, was recovered from the scene.
The suspect, Dzhokhar Tsarnaev, 19, told authorities that his older brother, Tamerlan Tsarnaev, 26, only recently recruited him to be part of the attack, two U.S. officials said.
The U.S. officials who spoke to The Associated Press were close to the investigation but insisted on anonymity because they were not authorized to discuss the case with reporters.
Tamerlan, whom authorities have described as the driving force behind the plot, was killed in a shootout with police. Dzhokhar is recovering in a hospital from injuries sustained during a getaway attempt.
Authorities had previously said Dzhokhar exchanged gunfire with them for more than an hour Friday night before they captured him inside a boat covered by a tarp in a suburban Boston neighborhood backyard. But two U.S. officials said Wednesday that he was unarmed when captured, raising questions about the gunfire and how he was injured.
More than 4,000 mourners at the Massachusetts Institute of Technology paid tribute to a campus police officer who authorities say was gunned down by the bombing suspects.
Among the speakers in Cambridge, just outside Boston, was Vice President Joe Biden, who condemned the bombing suspects as "two twisted, perverted, cowardly, knockoff jihadis."
Investigators have said the brothers appeared to have been radicalized through jihadist materials on the Internet and have not tied them to a terrorist group.
Dzhokhar told the FBI that they were angry about the U.S. wars in Afghanistan and Iraq and the killing of Muslims there, officials said.
How much of those conversations will end up in court is unclear. The FBI normally tells suspects they have the right to remain silent before questioning them so all their statements can be used against them.
Under pressure from Congress, however, the Department of Justice has said investigators may wait until they have gathered intelligence about other threats before reading those rights in terrorism cases. The American Civil Liberties Union has expressed concern about that.
Regardless, investigators have found pieces of remote-control equipment among the debris and were analyzing them, officials said. One official described the detonator as "close-controlled," meaning it had to be triggered within several blocks of the bombs.
They also recovered a 9 mm handgun believed to have been used by Tamerlan from the site of a Thursday night gunbattle that injured a Massachusetts Bay Transportation Authority officer.