A bomb detonated in a train carriage between the central metro stations Avtozavodskaya and Paveletskaya in February, and another bomb went off near the entrance to the Rizhskaya station in northern Moscow in August.
A state prosecutor said Tuesday that Murat Shavayev, Tamby Khubiyev and Maxim Panaryin - three key suspects - should be given life sentences for involvement in the attacks, which killed a total of 49 people and injured more than 300 others.
"Today, Tamby Khubiyev's lawyer reminded the court during deliberations that his client fully admitted to his guilt and proactively helped the investigation," Igor Trunov said, adding that the defendant asked the judge for leniency.
The suspects are facing charges of terrorism, murder, affiliation with a criminal group, illegal possession of arms, and the making of an explosive device. One of the co-defendants, Shavayev, continues to maintain his innocence and has asked the court to be cleared of all charges.
The third defendant, Maxim Panaryin, has partially admitted to his guilt.
Trunov supported the prosecutor's request for life sentences, and asked that the court have the defendants pay 36,200,000 rubles ($1.37 million) in damages on 12 claims.
He said the defendants will make final statements in the Moscow City Court, and the verdict will follow shortly.
The defendants are also suspected of involvement in a series of terrorist attacks at bus stops in the southwestern city of Voronezh and in Krasnodar, in Russia's south.
