A convicted Bosnian war criminal living in Jacksonville was sentenced to 18 months in prison in federal court Monday for falsely obtaining U.S. citizenship.

Slobo Maric, 56, pleaded guilty in July 2016 to charges of unlawfully gaining citizenship by failing to disclose during his naturalization process that he was a prison guard in the Bosnian Army in the 1990s and a convicted war criminal, the Department of Justice said.

He's been a citizen since 2002.

In 1993, Maric served as second-in-command to the warden of a Bosnian Serb jail that housed captured Bosnian Croat soldiers, officials said. Guards in the facility regularly beat and humiliated inmates, spitting on them and calling them ethnic slurs.

During the Bosnian War from 1992-1995, Bosnian Serbs participated in an ethnic cleansing campaign against both Muslim Bosniaks and Bosnian Croats. Over 8,000 civilians were murdered and about 25,000-30,000 Muslim Bosniaks were forced from the area.

Maric chose which inmates would be tortured and participated in many beatings at the jail, even sending some prisoners to deadly work duty on the front lines of the war, the Department of Justice said.

He was charged in Bosnia and, after fleeing, convicted while living in the U.S. Court documents said that Maric knew about his conviction and failed to tell the U.S. government while applying for citizenship.