Federal investigators identified one of the attackers as Dzhanet Abdurakhmanova, 17, of Dagestan and said they were still trying to identify the second bomber and track down the organizers of the attack.
Dagestan, one of the predominantly Muslim provinces in Russia's volatile North Caucasus region, was the site of two suicide bombings on Wednesday that killed 12 people, mostly police officers. Another explosion there Thursday killed two suspected militants.
The Kommersant newspaper published what it said was a picture of Abdurakhmanova, also known as Abdullayeva, dressed in a black Muslim headscarf and holding a pistol. A man with his arm around her, also holding a gun, is identified as Umalat Magomedov, whom the paper described as an Islamist militant leader killed by government forces in December.
The paper said the second subway bomber has been has been tentatively identified as 20-year-old Markha Ustarkhanova from Chechnya, the widow of a militant leader killed last October while he was preparing to assassinate Chechen President Ramzan Kadyrov, who is backed by the Kremlin.
The subway suicide bombings - the first such attacks in Moscow since 2004 - refocused attention on the violence that for years has been confined to the North Caucasus.
A Chechen militant leader on Thursday claimed responsibility for the subway bombings. Federal Security Service director Alexander Bortnikov said some terror suspects in the subway bombings had been detained, but did not elaborate.
Female suicide bombers from the North Caucasus are referred to in Russia as "black widows" because many of them are the wives, or other relatives, of militants killed by security forces.
Medvedev and Prime Minister Vladimir Putin have called for the terrorists to be unceremoniously destroyed. On Friday, Medvedev broadened the targets to include their accomplices, even those who help terrorists in tangential ways.
"In my opinion, we have to create such a model for terrorist crimes that anyone who helps them - no matter what he does, be it cook the soup or wash the clothes - has committed a crime," Medvedev said.
Russian police and security forces have long been accused of seizing people suspected of aiding militants. Some people have been tortured and many disappeared, and rights activists trying to document the abuses have also been slain, kidnapped or threatened.