An influential US lawmaker has said there is no indication that the Chechen brothers practiced bombing before carrying out the strike.
The two Chechen brothers - one a naturalised resident and other a lawful resident - allegedly constructed sophisticated weapons inside the US, a top American Senator has said.
Boston bombing suspect Dzhokhar Tsarnaev remained in serious condition in hospital unable to answer questions on the devastating attack, officials said.
A 20-year-old Lithuanian woman, suspected to be linked to twin suicide blasts in Moscow metro last month in which 40 people were killed, has been detained, a media report said on Sunday.
Two suicide bombers killed 12 people, including nine police officers in southern Russia on Wednesday, the same day a Chechen militant leader claimed responsibility for deadly subways bombings in Moscow that shocked the nation two days before.
Day in Pics: 18th April
Showbiz World - April 18, 2015
PM Modi in Canada