Max Shatto, 3, who was adopted from Russia, lived in Texas with his adoptive parents.
Deputies lined up to use Max Shatto's death to justify the ban on US adoptions of Russian children.
Laura Shatto said she had found him unconscious outside the family's home and he died later in hospital.
Max Shatto, adopted from a Russian orphanage, died in January age three, soon after Russia banned US adoptions.
News of Max Shatto's death led to an angry reaction in Russia, where he was known as Maxim Kuzmin.
Max Shatto's death increased tensions between Moscow and the US, which were already high after the Russian ban on US adoptions.
On Saturday, he returned to Twitter to say that Russian legal officials should seek access to all the documents surrounding Max Shatto's death.
On Monday, the Ector County district attorney said a grand jury declined to indict Laura and Alan Shatto, the adoptive parents of 3-year-old Max Shatto.
Max Shatto, adopted from a Russian orphanage, died on 21 January.
Russian politicians have been quick to seize on Max Shatto's death as a clear justification for their hardline stance, says the BBC's Daniel Sandford in Moscow.
Max Shatto and his younger brother Kristopher were adopted from an orphanage in north-west Russia last year by Alan and Laura Shatto, who live in Gardendale, Texas.
Max Shatto, born Maksim Kuzmin, and his younger brother Kristopher were adopted from an orphanage in north-west Russia last year by the Shattos, who live in Gardendale, Texas.
Four doctors in Texas concluded that Max Shatto, born Maksim Kuzmin, had died accidentally from a torn artery in his abdomen and had bruises consistent with injuring himself, a statement said.
Last month, Maz Shatto's mother Yulia Kuzmina, went on Russian state TV to complain that she had no idea her children had been taken to the US. She said she wanted to raise her surviving son, although it later emerged she was a recovering alcoholic.
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