The mother of the two brothers suspected of the Boston Marathon bombing has said she is "sure that (her) kids were not involved" in the blasts.
In a tearful press conference, Zubeidat Tsarnaev said she would have noticed if her sons had been planning such an attack, saying: "Any change, we should feel, I should feel it."
More top news
A freezing, frosty night for some of us, milder for others
Researchers are developing vaccines for new, emerging and unknown diseases before they cause global health emergencies.
Barack Obama urged Donald Trump to "go forward with his vision and his values", as he warned of "complexities" in office.