But Astokhov said Russian doctors found "some scars and some bodily injuries," including marks on his leg and hands. It was unclear, he said, what kind of marks they were.
"I don't know exactly, but there are some scars of two or three months old," he said.
In a video taped Friday by Russian officials and obtained by ABC News, Astokhov asked Artyem if he'd been hit by Hansen. He said no, but that Hansen had pulled his hair.
In Hansen's note to Russian officials, she called her son "dangerous."
"I no longer wish to parent this child," Hansen's note read.
"This child is mentally unstable," Hansen wrote to the Russian Ministry of Education. "He is violent and has severe psychopathic issues/behaviors. I was lied to and misled by the Russian orphanage workers and director regarding his mental stability and other issues."
Nancy Hansen, ABC News has learned, contacted Russian lawyer Karina Krasnova through e-mail a month before Artyem was put on the plane asking about legal options to annul the adoption.
"Their relationship with the adopted boy had reached a dead end," Krasnova said. "When this woman encountered massive problems, nobody lent her a helping hand. I think this was an act of desperation by the family."
Hansen's actions have inflamed already sensitive relations between U.S. and Russia over adoptions of Russian children to Americans. Russian officials have called for the halt of such adoptions while the case is investigated.
More than a dozen Russian children have died in the hands of their American adopters.
U.S. Ambassador to Russia John Beyrle said he also wants to investigate Artyem's case.
Several Russian families have come forward to adopt the boy, now Astokhov's preference. Beyrle said that might be acceptable, but Artyem is still torn between two countries.
"As soon as he sets foot on American soil having been legally adopted, he becomes an American citizen. So he is now in Russia, maintains that American citizenship," he said. "We have responsibilities and we have some rights. But we have no doubt that he's being well cared for right now.
"Our main concern is making sure that Justin Artyem is in safe hands," he said, "and has a chance to put all this behind him and get on with a normal life."
A delegation from the United States is expected to arrive in Russia to begin discussing international adoptions and Artyem's case.
ABC News' Zoe Magee, Desiree Adib and Kari Pricher contributed to this story.