The mother of the Boston Marathon bombing suspects was added to a federal terrorism database about 18 months before the attack, US government officials have said.
Two government officials said the CIA had Zubeidat Tsarnaeva's name listed along with that of her son Tamerlan Tsarnaev after Russia contacted the agency in 2011 with concerns that the two were religious militants about to travel to Russia.
Being in the classified TIDE database does not automatically mean a person is suspected by the US of terrorist activity and does not automatically subject someone to surveillance, security screening or travel restrictions.
The disclosure came as the surviving bombing suspect, Dzhokhar Tsarnaev, was moved overnight from a hospital to a federal prison medical centre, and as FBI agents searched for evidence in a landfill near the college he was attending.
Tsarnaev, 19, was taken from Beth Israel Deaconess Medical Centre, 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 Centre Devens outside Boston, said the US Marshals Service.
FBI agents picked through a landfill site on Friday 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 that killed three people and wounded more than 260 at the marathon finish line on April 15.
The brothers are ethnic Chechens from Russia who came to the US about a decade ago with their parents. Investigators have said it appears so far that the brothers were angry about the US wars in Afghanistan and Iraq and had been radicalised via Islamic material on the internet instead of any direct contact with terrorist organisations, but they warned it is still not certain.
A team of investigators from the US Embassy in Moscow has questioned both parents in Makhachkala, Russia, this week, spending many hours with the mother in particular over two days.
The suspects' father, Anzor Tsarnaev, said the questions were mostly about their sons' activities and interests.