SHELBYVILLE, Tennessee — U.S. authorities said they have not been able to question a Tennessee woman who returned her adopted 7-year-old son to Russia.

Bedford County Sheriff Randall Boyce said at a news conference that an attorney representing Torry Hansen said the 33-year-old woman refuses to talk to authorities unless a charge is filed. An adoption agency assigned to check on the family said officials there have not been able to contact her since late March.

The boy, Artyom Savelyev, flew unaccompanied to Moscow last week with a note from Hansen that said she no longer wanted him because he has psychological problems.

Boyce said the U.S. State Department knew of no federal laws that had been broken, so it was up to his department to determine whether charges could be filed. He is requesting medical information from Russian authorities about the boy and any records alleging that the boy was abused while in Tennessee.

"Nothing is simple about this," Boyce said Monday. "I haven't found anybody that knows them well. I don't know how long they've lived in this county."

A statement released by Adoption Assistance said the child appeared to be adjusting and the mother was enthusiastic during a visit by a social worker in January. But since late March, the agency has been unable to get in touch with her.

"Our agency worked diligently to locate the mother, including e-mails and calls to the client's mother, with no success," the statement said.

Torry's mother, Nancy Hansen, has said the child's violent episodes — which culminated in a threat to burn the family's home to the ground — terrified the family.

The agency said its services include providing families with education on issues such as attachment, bonding, behavioral matters and behaviors associated with institutionalized children.

"If this mother would have contacted us when the adjustment problems began, we would have worked with her on the issues or arranged alternative placement," the agency said.

District Attorney Chuck Crawford and other authorities are investigating abuse and child abandonment allegations.

Crawford said Monday that because the child flew alone out of Dulles International Airport outside Washington, charges might have to be filed there.