According to the court's Monday ruling, Kirill Kuzmin, or Kristopher Elvin Shatto as he is known in the U.S., must be transferred to the protection of the Russian state and his birth certificate modified to reflect his original name, birth place and parentage.
The judge has five days to write an analysis of the case before sending the decision to the Kuzmins' adoptive parents, Laura and Alan Shatto, who will have 30 days to appeal the decision, court press secretary Yulia Pron told Itar-Tass on Monday.
A Texas district court ruled in March that there were no grounds to file criminal charges against the Shattos after medical experts found that three-year-old Maxim had died from trauma received in an accident.
The Pskov court in March denied the prosecutors' petition to annul the adoption, citing a lack of evidence of cruel treatment or negligence by the Shattos, but in July granted an application for a second hearing.
Neither the Shattos nor their representatives were present during the latest round of court proceedings, which began on Dec. 20 and included testimony from regional prosecutors and social services as well as the orphanage in Pechory from which the Kuzmins were adopted.
"The court does not know the reasons for their absence," the court press secretary said.
The hearings were closed to the public on the request of prosecutors, who said that secrecy was necessary to protect the privacy of the litigants.
Kirill Kuzmin has lived with the Shattos in Gardendale, Texas, since he and his brother were adopted in 2012.
The political uproar over Maxim Kuzmin's death came just weeks after Russia banned all American adoptions of Russian children in what has widely been viewed as retaliation for the "Magnitsky List", a blacklist of Russian officials incriminated in reported human rights violations who are banned from entering or holding assets in the U.S.