A former Oahu Community Correctional Center prison guard began serving an 18-month prison term yesterday for sexually assaulting a male inmate.

A Circuit Court judge sentenced Ryan Mala­sig, 44, to five years of probation yesterday for second-degree sexual assault but ordered him to spend the first 18 months behind bars.

Malasig will be required to register as a sex offender.

Circuit Judge Richard Pollack also ordered Mala­sig to pay $5,265 in restitution to the Sex Abuse Treatment Center for the weekly therapy it has provided the victim and $370 to the victim for related medication.

“Mr. Malasig, you took gross advantage of your position to commit criminal conduct in this case on a very person that you were required to oversee and, in a sense, protect,” Pollack said.

The prosecution said Mala­sig forced the inmate, who lives as a female, to perform oral sex on him on Aug. 23, 2009, at OCCC. The inmate saved DNA from the incident on his shirt and presented it to police when the incident was reported.

Malasig resigned from his job in December 2009, and he was indicted last October. He pleaded no contest in January.

Deputy City Prosecutor Leilani Young asked Pollack to impose the maximum 10-year prison term because when court officials interviewed Mala­sig for his pre-sentencing report, he denied having sex with the inmate.

However, Malasig admitted his conduct yesterday and apologized in court to the victim and his family members as well as to his own family members pres­ent.

“It was a bad decision on my part, and I wanted to let you guys know that I’m completely sorry for what had happened,” Mala­sig said.

In a letter to the court, the victim said he has flashbacks and nightmares of the assault, gets depressed and contemplates suicide.