(CNN) A former Georgia police officer was sentenced to 12 years in prison Friday for the killing of a mentally ill, unarmed and naked black man in 2015.

DeKalb County Superior Court Judge LaTisha Dear Jackson gave Robert "Chip" Olsen a 20-year term, with 12 years to be served in custody. Under the sentence, Olsen is prohibited from working in law enforcement, possessing firearms or profiting from the case.

Dear Jackson praised what she said was the strength, fortitude and compassion of the family of the victim, 26-year-old Afghanistan war veteran Anthony Hill. She said she had also watched the defendant closely during the trial.

"Many might have thought you were stoic and void of emotion," the judge told Olsen. "From the time opening statements started, I saw the tears that you've had. I saw how you replayed March 9, 2015, in your head."

Prosecutors had asked the court for a 25-year sentence with five years probation.

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