The worried mother of a U.S. soldier in Russian custody said Wednesday that her son “was lured” there by a Russian woman he had been seeing in South Korea for over a year and that he’s being held on trumped-up charges of stealing roughly $100 from her.

Melody Jones said she thinks her son, Staff Sgt. Gordon Black, was set up by his girlfriend, whom she identified as Aleksandra Vashchuk.

“I think she convinced him to come there,” Jones said in a video interview from her home in Cheyenne, Wyoming. “He wanted to see her for the last time before going home, and so he went there.”

The Russians detained Black, 34, on theft charges last week after he traveled from the military base in South Korea where he had been stationed to the far eastern Russian city of Vladivostok.

A Defense Department spokesperson said Tuesday that the Army is investigating whether Russia’s intelligence services specifically targeted Black.