MOSCOW, February 21 - RAPSI. The birth mother of Maxim Kuzmin who was adopted by the Shatto family in the US has asked the authorities to restore her parental rights to Maxim's younger brother, Kirill, who is still living with the American family.

Russian Children's Rights Commissioner Pavel Astakhov has announced that Yulia Kuzmina, the birth mother of the boy who died in the United States, has changed her irresponsible way of life and has asked the authorities to restore her parental rights to her other son, Kirill.

Astakhov said she could be granted her request if there are sufficient grounds for it.

The Social Security Department of the Pskov Region, where the Kuzmin brothers lived before they were adopted, has appealed to the courts to cancel the adoption of Kirill Kuzmin, the regional government website said on Wednesday.

Their statement claims that there are grounds for cancelling his adoption.

The Federation Council, the upper house of Russia's parliament, is forming a working group to investigate the reasons behind the deaths of Russian orphans in the United States.

Astakhov said  that the child had been given powerful “psychotropic substances” and was badly beaten before his death, which reportedly occurred on January 21.

Alan and Laura Shatto also adopted Maxim's his younger brother, two-year-old Kirill, who is still living with them.

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.