Former state prison guard Irwin Ah-Hoy is serving an 18-month prison term at the Federal Detention Center for sexually assaulting an inmate at the Women’s Community Correctional Center.

State Circuit Judge Karen Ahn sentenced Ah-Hoy, 51, last week to five years of probation and concurrent 18-month prison terms for two counts of second-degree sexual assault and two counts of third-degree sexual assault. The prison time was a condition of his probation.

The state Department of Public Safety said it sent Ah-Hoy to the Federal Detention Center because of space limitations at Oahu Community Correctional Center. The DPS has a contract with the U.S. Bureau of Prisons to house Hawaii inmates with shorter sentences at the federal facility.

Ah-Hoy pleaded no contest in April, one week before he was scheduled to stand trial.

An Oahu grand jury returned an indictment against him in March 2013 charging him with sexually assaulting a WCCC inmate twice in March 2012, and fondling the same inmate during those incidents.

The city prosecutor said Ah-Hoy directed other staff at WCCC to send the inmate to him, then forced her into a staff-only bathroom and sexually assaulted her. The prosecutor said the inmate saved Ah-Hoy’s DNA from one of the encounters.

In March 2015 the inmate sued the state, Ah-Hoy, the WCCC warden and the director of the DPS. In her complaint she said she saved Ah-Hoy’s DNA and sent it to her criminal lawyer in Hilo, who turned it over to law enforcement.

The state later had the lawsuit transferred to federal court. A trial is scheduled for next July.

State prison officials released the victim on parole in September 2013.