A 28-year-old female school teacher may have been the second of two suicide bombers who killed 40 people on the Moscow metro last week, according to a Russian newspaper.
Russian investigators are looking into whether Maryam Sharipova was responsible for one of the blasts after her father said he recognised her in photos believed to be the remains of a bomber, circulated on the internet.
"My wife and I immediately recognised our daughter Maryam," Rasul Magomedov, a teacher in the North Caucasus province of Dagestan, told Novaya Gazeta.
"When my wife last saw our daughter she was wearing the same red scarf we saw in the pictures."
'No history'
Magomedov said his daughter graduated with a degree in mathematics and psychology from the Dagestan Pedagogical University in 2005.
She returned to her village, lived at home and taught computer science at a local school.
But her father said she never expressed any radical beliefs.
"I would really like the investigation to uncover the true picture of what happened. We cannot even suggest how Maryam could get to Moscow," he said.
Neave Barker, Al Jazeera's correspondent in Moscow, said: "Novaya Gazeta [is] one of the most well respected, independent, newspapers in Russia.
"The report ... says she [Sharipova] had no history of association with extremist groups, although her brother was believed to have been detained in connection with fighters operating out of the North Caucasus.
"So far the authorities haven't confirmed or denied questions as to whether Sharipova is the second suicide bomber to be identified."
The first bomb, which Magomedov believes was carried by his daughter, struck a packed Moscow metro train just before 0800 local time on Monday as it stood at the Lubyanka station, close to the headquarters of the FSB.
It killed at least 23 people.
A second bomb was detonated less than 40 minutes later in a train waiting at the Park Kultury metro station, killing at least another 12 people.
'Black widow'
The other bomber has been identified as Dzhanet Abdullayeva, a 17-year-old widow of a North Caucasus fighter.
Russian media has described Abdullayeva as a "black widow", the name given to suicide bombers whose partners have been killed by Russian forces in areas such as Chechnya, Dagestan and Ingushetia.
Photographs published on Friday showed Abdullayeva posing in an Islamic headscarf and holding a gun, sitting next to Magomedov.
Irina Gordienko, a Russian journalist who spoke to Magomedov, told Al Jazeera that the father could not understand how she got to Moscow.
Dagestan has been an epicentre of the almost daily violence that continues to rock the North Caucasus following two separatist wars in neighbouring
Chechnya.
The fighters are now seeking to create an Islamic state across the region.
Vladimir Putin, the Russian prime minister, has vowed to "drag out of the sewer" the organisers of the subway bombings, and Dmitry Medvedev, the president, has promised "crueller" measures to crack down on such attacks.
Human-rights groups accuse Russian security forces and police of stoking the unrest through extrajudicial killings, abductions and abuses in the North Caucasus.