BOSTON (AP) -- The Boston Marathon bombing suspects intended to blow up their remaining explosives in New York's Times Square, New York officials said Thursday.
New York Police Commissioner Raymond Kelly said Dzhokhar Tsarnaev told interrogators from his hospital bed that he and his older brother had decided spontaneously Thursday night to go to New York to detonate their remaining explosives -- a pressure-cooker bomb like the ones that blew up at the marathon, and five pipe bombs.
The plan fell apart after the Tsarnaev brothers were intercepted by police in a stolen car and got into a fierce gun battle that left Tamerlan Tsarnaev dead, Kelly said.
Dzhokhar, 19, is charged with carrying out the April 15 bombing that killed three people and wounded more than 260, and he could get the death penalty.
PHOTO GALLERY - The day of the attacks (http://bit.ly/15buUtp)
He was interrogated in his hospital room over a period of 16 hours without being read his constitutional rights. He immediately stopped talking after a magistrate judge and a representative from the U.S. Attorney's office entered the room and read him his rights, according to a U.S. law enforcement official and others briefed on the interrogation.
The developments in New York came as federal authorities in Washington were piecing together the case and whether there were any unconnected dots buried in U.S. government files that, if connected, could have prevented the attacks.
The federal government added Tamerlan's name to a terrorist database 18 months before the attacks, U.S. officials told The Associated Press.
Dzhokhar Tsarnaev told authorities that his older brother only recently recruited him to be part of the attack, two U.S. officials said Wednesday.
The CIA, however, named Tamerlan, 26, to a huge, classified database of known and suspected terrorists 18 months ago, officials said, an acknowledgment that will undoubtedly prompt congressional inquiry about whether the Obama administration adequately investigated tips from Russia that Tsarnaev had posed a security threat.
Shortly after the bombings, U.S. officials said the intelligence community had no information about threats to the marathon before the explosions.
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.
Investigators have said the brothers, Russian-born ethnic Chechens, appeared to have been radicalized through jihadist materials on the Internet and have found no evidence tying them to a terrorist group.
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.
The CIA made the request to add Tamerlan's name to the terrorist database after the Russian government contacted the agency with concerns that he had become a follower of radical Islam. About six months earlier, the FBI had separately investigated Tsarnaev, also at Russia's request, but the FBI found no ties to terrorism, officials said.
Officials say they never found the type of derogatory information on Tsarnaev that would have elevated his profile among counterterrorism investigators and placed him on the terror watch list.
Lawmakers who were briefed by the FBI said they have more questions than answers about the investigation of Tsarnaev. U.S. officials were expected to brief the Senate on the investigation Thursday.
Officials said Wednesday that Dzhokhar 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.
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.
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.
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.