Max Shatto died in January 2013.
Shatto's adoptive mother -- Laura Shatto -- reportedly found the toddler unresponsive at their Gardendale home.
Russian officials have accused the Shattos of abusing Max, 3, and giving him psychoactive drugs.
West Texas officials confirm that bruises were found on Max's body, but an autopsy is still pending to determine his cause of death.
Now, Max Shatto's biological mother is begging for the return of Max's young brother, who remains with the Shattos (who are also his adoptive parents).
The biological mother wrote the following in a letter to the Russian president: "Have found work and have the ability to provide for the child. Help me please, don't allow the death of my second child, Kirill."