FBI agents investigating the Boston Marathon bombings have questioned the wife of dead suspect Tamerlan Tsarnaev.
Local media report officers visited Katherine Russell after traces of female DNA were discovered on the bomb fragments.
Three people were killed and 260 injured in the bomb attack.
Dzhokhar Tsarnaev, the younger of the suspects, is recovering from gunshot wounds in a prison medical facility.
His elder brother was killed in a shootout with police in the Boston suburb of Watertown.
Officers say they believe there is a connection between Watertown and the two suspects.
Watertown is home to a Chechen community and the brothers are both ethnic Chechens.
Investigators have confirmed they have spoken to “Misha,” a man the brothers parents say radicalised Tamerlan and found no link between him and the deadly attack.