Ivan Mironov, detained December 11, 2006 after a lengthy man hunt, is the fourth suspect in the case and currently being held in a pre-trial detention center. He is suspected of attempted murder of Anatoly Chubais, chief executive of Unified Energy Systems (UES) of Russia in March 2005, when his car came under automatic gunfire near Moscow. Chubais was not injured in the attack.
The defense intends to appeal the ruling to a higher court.
"We will use all our efforts to get my son out of prison," Tatyana Mironova, the mother of Ivan Mironov, said adding that "This is revenge for his father and the case is purely political."
Mironov was arrested together with his father, Boris Mironov, a suspect in a separate inquiry into inciting inter-ethnic hatred. A former head of the Russian Print Media Committee, Boris Mironov is accused of making anti-Semitic speeches in 2003 while running for governor of Siberia's Novosibirsk Region.
Three other suspects in the case - two former officers of the Airborne Troops and one former officer of the General Staff - are already on trial by jury in the Moscow Region, in a closed hearing.
In late December last year the Moscow Region court dismissed the jury in the case on the demand of the prosecution, which alleged that some media outlets had published information on the hearing, even though the trial was held in a closed regime.
A lawyer for the defense said earlier the prosecutors' move could have been linked to the arrest of Ivan Mironov.
According to prosecutors, the suspects were motivated by extremist views and a violent dislike of Chubais, an architect of economic reforms in the 1990s that impoverished millions and gave vast fortunes to a handful of well-connected oligarchs. Chubais is now behind a series of unpopular decisions to hike electricity tariffs.