US prosecutors said on Monday that no charges will be made against the Texan couple in the case of the death of adopted Russian three-year-old Maksim Kuzmin, due to lack of evidence.

Ector County District Attorney Bobby Bland said the Alan and Laura Shatto will not be charged in the death of their adopted boy Max Alan Shatto (born Maksim Kuzmin) on 21 January. “The grand jury said there was insufficient evidence to charge them with anything”, Bland told the press.

The Russian Foreign Ministry is demanding a handover of all documentation relating to Maksim's death, saying not charging the family with a crime “raises serious questions.”

Laura Shatto had told the police that she had left Maksim with his 2-year-old brother to play outside their house and found him unresponsive moments later. The boy was pronounced dead shortly on arrival to the hospital. Although Maksim’s body showed bruises consistent with abuse, the doctors’ final word was that his death was an accident, following the final autopsy.

The cause of death, they said, is blunt force trauma. One of the boy’s arteries had received a fatal laceration, possibly an accident with playground equipment. Maksim appears to have hurt himself in the 10 minutes he was alone. Bland also said the boy was underweight, and therefore more susceptible to heavy injury.

No information on what charges were being considered was given by the District Attorney.

The Shattos are avoiding talking to the media; their voicemail message continues to say they have no comment.

The boy’s death on January 21st took center stage in the debate over whether Americans should be allowed to adopt Russian children. Although domestic abuse has not been proven, the case only adds to the number of which have been documented. A recent incident relates to the summer of 2008, when a father left his adopted Russian 21-month-old in a locked car on a hot day, resulting in the child’s death.

Russian authorities and media initially placed the blame for Maksim’s death with the Shattos. The case was used by them to justify a recently passed law banning American adoptions of Russian children. The ban was put in place in December of 2012, in response to the high-profile deaths of Russian children adopted to America, as well as US reluctance to cooperate with Russian authorities in investigating the cases.

The feeling of resentment in Russia towards Americans adopting children from the country has been growing steadily as cases of abuse drew wide publicity, that’s despite the number of abuse cases being relatively small over the last two decades. The country worries for the fate of some of its 60,000 children currently living in the US, at least 20 of whom have died because of ill treatment or in accidents. The Russian Foreign Ministry’s Special Representative for Human Rights, Konstantin Dolgov, has strongly condemned Maxim’s death, calling it “yet another case of inhuman treatment”.

An investigation into the nature of Maksim’s bruises is still on-going, according to Texas Child Protective Services spokesman Patrick Crimmins. He did not say when the investigation would be concluded.  A separate investigation of the US adoption agency that handled the case was concluded with the agency having been cleared of any wrongdoing.

Maksim’s biological mother has appeared in the media, desperately pleading for her other son, two-year-old Kirill – also with the Shattos – to be returned to her. Yulia Kuzmina was stripped of her parental rights due to negligence and drinking problems. However, now she claims to be a new person on the road to recovery, having quit drinking and getting a job. None of her claims have proved to be true.

Russian and US officials have since expressed their desire for continuing partnerships in other areas and for tension over Maksim’s case not to escalate into a further diplomatic deadlock.

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