BOSTON (AP) -- Boston Marathon bombing suspect Dzhohkar Tsarnaev was moved from a hospital to a federal prison medical center, while FBI agents searched for evidence Friday in a landfill near the college he was attending.
U.S. officials, meanwhile, said that the bombing suspects' mother had been added to a federal terrorism database about 18 months before the deadly attack - a disclosure that deepens the mystery around the Tsarnaev family and marked the first time American authorities acknowledged that Zubeidat Tsarnaeva had come under investigation before the tragedy.
The news is certain to fuel questions about whether the Obama administration missed opportunities to thwart the April 15 bombing that killed three people and wounded more than 260 at the finish line of the Boston race.
Tsarnaev, 19, was taken overnight from Beth Israel Deaconess Medical Center, where he was recovering from a gunshot wound to the throat and other injuries suffered during a getaway attempt, and transferred to the Federal Medical Center Devens, about 40 miles from Boston, the U.S. Marshals Service said. The facility at the former Fort Devens Army base treats federal prisoners.
Also, FBI agents picked through a landfill near the campus of the University of Massachusetts Dartmouth, where Tsarnaev was a student. FBI spokesman Jim Martin would not say what investigators were looking for.
Tsarnaev is charged with joining with his older brother, now dead, in setting off the shrapnel-packed pressure-cooker bombs.
The brothers are ethnic Chechens from Russia who came to the U.S. about a decade ago with their parents. Investigators have said it appears that the brothers were angry about the U.S. wars in Afghanistan and Iraq.
Two government officials, speaking on condition of anonymity because they were not authorized to speak publicly about the investigation, said the CIA had Zubeidat Tsarnaeva's name added to the terror database along with that of her son Tamerlan Tsarnaev after Russia contacted the agency in 2011 with concerns that the two were religious militants.
About six months earlier, the FBI investigated mother and son, also at Russia's request, one of the officials said. The FBI found no ties to terrorism. Previously U.S. officials had said only that the FBI investigated Tamerlan.
In an interview from Russia, Tsarnaeva said Friday that she has never been linked to terrorism. She said it would not surprise her if she were listed in a U.S. terror database.
"It's all lies and hypocrisy," she told The Associated Press from Dagestan. "I'm sick and tired of all this nonsense that they make up about me and my children. People know me as a regular person, and I've never been mixed up in any criminal intentions, especially any linked to terrorism."
Tsarnaeva faces shoplifting charges in the U.S. over the alleged theft of more than $1,624 worth of women's clothing from a Lord & Taylor department store in Natick, Mass., in 2012.
Earlier this week, she said she has been assured by lawyers that she would not be arrested if she traveled to the U.S., but she said she was still deciding whether to go. The suspects' father, Anzor Tsarnaev, said that he would leave Russia soon for the United States to visit one son and lay the other to rest.
A team of investigators from the U.S. Embassy in Moscow has questioned both parents in Russia this week, spending many hours with the mother in particular over two days.
Also on Thursday, officials said that three days after the Boston attack, the Tsarnaev brothers planned to drive to New York and bomb Times Square in a spur-of-the-moment scheme that fell apart almost immediately when they realized the SUV they had hijacked was low on gas. They had five pipe bombs and a pressure-cooker explosive in the vehicle, police said.
"We don't know if 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."
New York Police Commissioner Raymond Kelly said Dzhokhar Tsarnaev told interrogators from his hospital bed that he and his brother decided the night of April 18 to launch an attempt in New York. But when the Tsarnaev brothers stopped at a gas station on the outskirts of Boston, the carjacking victim they were holding hostage escaped and called police, Kelly said.
Later that night, police intercepted the brothers in a gun battle that left 26-year-old Tamerlan Tsarnaev dead.
The word of a short-lived plan to bomb Times Square made some New Yorkers shudder at the thought of another terrorist attack on the city.
Outside Penn Station, Wayne Harris, a schoolteacher from Queens, said: "We don't know when a terrorist attack will happen next in New York, but it will happen. It didn't happen this time, by the grace of God. God protected us this time."