The parents of the Boston Marathon bombing suspects have left their home in Dagestan for another part of Russia, the suspects' mother Zubeidat Tsarnaev told CNN Friday. She said the suspects' father, Anzor Tsarnaev, is delaying his trip to the United States indefinitely.
Meanwhile in Boston, their son Dzhokhar, the surviving bombing suspect, was transported to a federal detention center hospital, a federal law enforcement official said Friday. His brother and alleged co-conspirator Tamerlan was killed in a gun battle with police last week.
"Dzhokhar Tsarnaev has been transported from the Beth Israel Deaconess Medical Center and is now confined at the Bureau of Prisons facility FMC Devens at Ft. Devens, Massachusetts," said Drew Wade, spokesman for the U.S. Marshals.
Their father, Anzor, was to fly to the United States as soon as Friday to cooperate in the investigation into the attacks. But his wife called an ambulance for him Thursday.
She told CNN's Nick Paton Walsh that her husband was delaying the trip for health reasons. She wouldn't elaborate.
Anzor Tsarnaev agreed to fly to the United States after FBI agents and Russian officials spoke with them for hours this week at the family's home.
Russian authorities have previously expressed suspicions that his wife, Zubeirdat Tsarnaev, and their elder son, Tamerlan, the deceased suspect in the attacks, were following radical ideologies.
The mother will not be flying to the United States, where she is wanted on felony charges of shoplifting and destruction of property.
Spontaneous plan to attack New York City
New York City was the next target for the Boston Marathon bombing suspects. It was a spontaneous idea, wounded suspect Dzhokhar Tsarnaev, 19, told investigators from his hospital bed.
He and his older brother Tamerlan, who died at age 26 while allegedly fleeing police last week, still had half a dozen bombs left. But a botched carjacking spoiled the impromptu road trip to Times Square, Tsarnaev said.
"We don't know that we would have been able to stop the terrorists had they arrived here from Boston," Mayor Michael Bloomberg said. "We're just thankful that we didn't have to find out that answer."
Before forcing their way into the vehicle the night of April 18, the brothers shot dead a campus police officer at the Massachusetts Institute of Technology, police said.
The Mercedes SUV ran low on fuel, and when they pulled in to a service station, the vehicle's owner escaped. Shortly thereafter, police were on their trail, and authorities say the men were throwing the bombs out the vehicle's window at them.
A previous trip
There is no evidence that New York City is a target of a terror attack stemming from the Boston bombings, New York City Police Commissioner Ray Kelly said. Still, he said authorities are investigating two visits that the surviving suspect made to New York City last year.
In one of those trips, in April 2012, Dzhokhar Tsarnaev is photographed in Times Square. Another person pictured in that photo has been in federal custody for seven days, on alleged visa violations.
The man, whom a federal law enforcement source said Dzhokhar Tsarnaev shared a cell phone with, was originally detained April 19 with another person when federal agents swarmed a residence thinking the younger suspect might be inside, a federal law enforcement source said.
Neither of the two detained men -- both foreign exchange students from Kazakhstan at the University of Massachusetts-Dartmouth, where Dzhokhar Tsarnaev was also enrolled -- has been linked to the Boston Marathon attack. Yet investigators hope they can better piece together the suspects' movements before and after the marathon.
"These guys are not being cut loose immediately, and there's a reason why," the federal law enforcement source said.
Sources: Russia raised concerns about mother, son
The probe into the Boston attacks has also been focused some 5,500 miles away in the semiautonomous Russian republic of Dagestan, where the suspects' parents live.
Their mother, Zubeidat Tsarnaev, told CNN's Nick Paton Walsh on Thursday that she didn't want to accept the reality of the bombing, saying it was fake. She has seen a video pushing the wild idea, she said, adding that there was no blood and that paint was used instead.
She broke down when she spoke of the victims.
"I really feel sorry for all of them. Really feel sorry for all of them," she said, her voice cracking even as she remained resolute that her sons were not involved.
The family lived in Massachusetts before Zubeidat Tsarnaev jumped bail after her arrest on shoplifting and property damage charges in 2012. The parents moved the same year to Dagestan.
The Tsarnaevs are originally from the embattled Russian republic of Chechnya but fled from the brutal wars there in the 1990s. The two brothers were born in Kyrgyzstan and moved at different times to the United States.
Zubeidat Tsarnaev and her older son were both added by U.S. authorities to the Terrorist Identities
Datamart Environment, or TIDE, database in 2011 -- a collection of more than a half million names maintained by the National Counterterrorism Center, an intelligence official said.
Russian authorities had raised concerns to U.S. authorities about her and her son, sources told CNN. But a U.S. official said that the Russian's case at the time was "thin."
Zubeidat Tsarnaev said the FBI had visited her family "several times" in 2011 with questions about her older son's "Islamic interests."
Putin: 'We were right'
Russian President Vladimir Putin on Thursday urged closer cooperation between other countries' security services in the wake of the Boston attack.
"If we combine our efforts, we will not suffer blows like that," he said during a live televised call-in session in Moscow on Thursday.
In his first on-camera comments since the bombing, Putin also lashed out against those in the West who have slammed Russia for human rights abuses in its actions toward Chechnya.
"Russia is among the first victims, and I hate it when our Western partners call our terrorists -- who committed some heinous crimes in Russia -- when they call them freedom fighters and never call them terrorists. They supported them," said Putin, accusing unnamed people or groups of providing Russia's foes with political, financial and "media" support.
U.S. authorities have come under fire at home, with lawmakers asking if the FBI and CIA failed to share information. Sources told CNN that Russia had separately asked the FBI and the CIA to look into Tamerlan Tsarnaev in 2011.
Sources: Suspect was unarmed in boat
More details, meanwhile, continue to emerge about the April 15 bombings as well as authorities' engagement days later with the two suspects.
A law enforcement official told CNN Thursday that at least one of the two bombs, the second to explode, was detonated by remote control.
The twin blasts killed three people and injured more than 260 others, 14 of whom had limbs amputated. As of Thursday evening, 34 of those wounded were still being treated at Boston hospitals, including one patient in critical condition.
The manhunt for those responsible ended last Friday, when Dzhokhar Tsarnaev was captured following a tense standoff after he'd hidden in a boat in the yard of a home in the Boston suburb of Watertown, Massachusetts.
The teenager was unarmed when he was wounded in a barrage of gunfire, and there was no firearm found in the boat, said several sources from difference agencies familiar with the investigation.
CNN's Drew Griffin, Dave Alsup, Carol Cratty, Nick Paton Walsh, Brian Todd, Barbara Starr, Susan Candiotti and Ben Brumfield contributed to this report.