MOSCOW, February 22 - RAPSI. The Prosecutor's Office of the Pskov Region has filed a lawsuit against US nationals Alan and Laura Shatto to cancel the adoption granted in September 2012 of two-year-old Kirill Kuzmin, the younger brother of Maxim, who died in the United States in January 2013.

The Prosecutor General's Office said on Thursday that they feared for Kirill's life, while he lived with his adoptive US family.

The Pskov prosecutors ask the court to revoke Kirill's adoption, restore his Russian given and family names and patronymic, place of birth and details of his birth parents in his birth certificate. They ask that Kirill be turned over to Russian custody offices for his subsequent re-adoption in Russia or return to his birth mother.

Russian Children's Rights Commissioner Pavel Astakhov announced Monday that three-year-old Maxim (renamed Maxim Shatto by his adoptive parents) had been fed strong psychotropic medication and beaten prior to his death, which is believed to have occurred on January 21.

Astakhov initially declared that Maxim had been killed by his adoptive mother, but later admitted that an investigation remained underway. Maxim's younger brother, Kirill, is still living with Alan and Laura Shatto.

The Texas Child Protective Services (CPS) is investigating the death of Maxim Kuzmin, a CPS representative told RIA Novosti in Washington on Monday.

A number of high-profile cases of abuse and death of adopted Russian children in US homes have strained US-Russian diplomatic ties over recent years.

In response to the growing number of these incidents, Russia recently enacted the Dima Yakovlev Law, named after a two-year-old Russian boy who died of heatstroke after his adoptive US father left him locked in a car for hours on a hot summer day in 2008. His father was later acquitted on charges of involuntary manslaughter, inciting a wave of criticism in Russia.

Around 60,000 Russian children have been adopted by American families over the past two decades, of which 19 have died at the hands of their parents.