US soldier sentenced to Russian penal colony, local media reports

Staff Sgt. Gordon Black's trial had begun on Monday in Vladivostok.

"The Pervomaisky District Court of Vladivostok sentences Black to almost four years in a penal colony," an Interfax correspondent reported from inside the courtroom.

Black was arrested in May. His trial had started on Monday, with Black pleading partially guilty to charges of theft, but not admitting to the charges of assault or threat to kill, according to Russian media.

The staff sergeant was stationed in South Korea and was on temporary leave when he entered Russia, two U.S. officials told ABC News in May. Black had not been granted permission to travel to Russia, the officials said.

Black's mother, Melody Jones, told ABC News that her son had been visiting his girlfriend.

He was accused of taking money from the woman and was detained in Vladivostok -- near the borders North Korea and China -- on charges of criminal misconduct.

ABC News' Joe Simonetti, Leah Sarnoff, Mark Guarino and Anne Flaherty contributed to this report.