MOSCOW (AP) — An American imprisoned in Russia after being convicted of beating a police officer had his sentence extended Wednesday when he was found guilty of assaulting prison guards, news reports said.

Robert Gilman, who was identified in Russian media as a former U.S. Marine, was initially handed a 3 1/2-year sentence in 2022 when he was convicted of beating a police officer after being taken off a train for causing a disturbance.

He later was convicted of attacking a prison inspector during a cell check, beating an investigator and assaulting a guard, and was sentenced in October 2024 to eight years and one month.

On Wednesday, a court in Voronezh, a region in southwestern Russia where Gilman is serving his sentence, extended his term to 10 years after he was found guilty of beating two prison guards.

The business daily Kommersant reported that Gilman pleaded guilty to the charges and apologized to the guards he was charged with assaulting. The newspaper said he explained his actions by saying he wanted to stay in the prison where he was serving his sentence and avoid being moved to another penitentiary.

Gilman is one of a few Americans who remain in Russian custody after a series of high-profile prisoner exchanges with the United States in recent years.