(CNN) -- The death of a Russian boy who was adopted by an American couple has been ruled accidental, the district attorney of Ector County, Texas, told CNN on Friday.
The announcement came after an autopsy was completed on Max Shatto, 3.
District Attorney Bobby Bland said four pathologists and the Ector County medical examiner determined the cause of death, which they attributed to a laceration of a small bowel mesentery artery due to blunt trauma to the abdominal area. The bruising was consistent with a "self-inflicted" injury, Bland said.
A statement from the Ector County Sheriff's Office said that the boy "had previously been seen for a behavioral disorder that manifested itself in self-injury and these bruises were consistent with that diagnosis."
Toxicology reports were negative and there were no substances found that could have contributed to the child's death.
The sheriff's office said it and other agencies would continue their investigation into the case.
The boy's death drew international attention after a Russian government child advocate said that the boy was "killed" or "murdered."
At a press conference last week, Children's Rights Commissioner Pavel Astakhov said he tweeted those words based on the initial reports he received about the death. He acknowledged he may have spoken too soon.
Still, he wants his country to ban all international adoptions of Russian children.
The boy was born on January 9, 2010, and died on January 21, Russian officials have said.
The boy's death aggravated U.S. State Department efforts to push through more than 500 adoption cases in which American families have already begun the process to adopt a Russian child before Moscow in December passed a law banning adoptions of Russian children by Americans.
That pending law would ban adoptions by Americans ostensibly because of documented cases of abuse by adoptive parents. But others say the Russian move is in retaliation for a U.S. law that places restrictions on Russian human rights abusers.
Americans adopted close to 1,000 Russian children last year, according to State Department figures.
Though the number has been dropping in recent years, Russia remains the third most popular foreign country -- after China and Ethiopia -- for U.S. foreign adoptions.