BOSTON (AP) -- 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 right to keep quiet and seek a lawyer, U.S. officials said Wednesday.
Once Dzhokhar Tsarnaev was read his rights on Monday, he immediately stopped talking, according to four officials of both political parties who were briefed on the interrogation but insisted on anonymity because the briefing was private.
After roughly 16 hours of questioning, investigators were surprised when a magistrate judge and a representative from the U.S. Attorney's office entered the hospital room and read Tsarnaev his rights, the four officials and one law enforcement official said. Investigators had planned to keep questioning him.
It is unclear whether any of this will matter in court since the FBI says Tsarnaev confessed to a witness and U.S. officials said Wednesday that physical evidence, including a 9 mm handgun and pieces of a remote-control device commonly used in toys, was recovered from the scene.
But the debate over whether suspected terrorists should be read their Miranda rights has become a major sticking point in the debate over how best to fight terrorism. Many Republicans, in particular, believe Miranda warnings are designed to build court cases, and only hinder intelligence gathering.
Christina DiIorio Sterling, a spokeswoman for U.S. Attorney Carmen Ortiz, said in an email, "This remains an ongoing investigation and we don't have any further comment."
Before being advised of his rights, the 19-year-old suspect told authorities that his older brother, Tamerlan Tsarnaev, 26, only recently had recruited him to be part of the attack, two U.S. officials said.
The CIA, however, named Tamerlan to a terrorist database 18 months ago, officials said Wednesday, an acknowledgment that will undoubtedly prompt congressional inquiry about whether investigators took warnings from Russian intelligence officials seriously enough.
The U.S. officials who discussed the terrorist database and other details of the investigation are in addition to those who discussed the Miranda warning. They were close to the investigation and insisted on anonymity because they were not authorized to discuss the case with reporters.
Tamerlan Tsarnaev, 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 suffered 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 found no evidence tying 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.
Dzhokhar's public defender had no comment on the matter Wednesday. His father has called him a "true angel," and an aunt has insisted he's not guilty.
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.
That evidence could be key to the court case. And an FBI affidavit said one of the brothers told a carjacking victim during their getaway attempt, "Did you hear about the Boston explosion? I did that."
Officials 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, two U.S. officials said.
The officials told the AP that no gun was found in the boat. Boston police Commissioner Ed Davis said earlier that shots were fired from inside the boat.
Asked whether the suspect had a gun in the boat, Davis said, "I'm not going to talk about that."
Kurt Schwartz, director of the Massachusetts Emergency Management Agency, did respond to the report.
"Within half a mile of where this person was captured, a police officer was shot. And I know who shot him." Schwartz said. "And there were three bombs that went off, and I know where those bombs came from. ... To me, it does not change anything. This guy was captured alive and will survive. True or not true, it doesn't change anything for me."