The photo of a 17-year-old woman thought to be one of the two female suicide bombers who struck in Moscow has appeared in the media.
The woman has been named by Russian authorities as the widow of an Islamist militant leader killed in Dagestan late last year.
Another 20-year-old woman is said to have been identified as the other bomber. She is also reported to be the widow of a dead militant.
The suicide bombings left at least 40 people dead and dozens more injured.
An Islamist Chechen rebel leader claimed responsibility for the attacks and threatened further bombings in other Russian cities.
He said the strikes were revenge for Vladimir Putin’s policies in the North Caucasus.
Amid fears of a new rebel bombing campaign in Russia, security has been stepped up in public places, as police try to clamp down on known militant networks.