Assuming the person is truly guilty and is of sound mind, I would proscribe a certain amount of time in prison both to restore some dignity to the victim and to ensure the guilty person can not do the same thing to other people.
I would NOT subject him/her to any excessive or cruel punishment, just enough to make the person understand the error of his/her ways and to turn him/her back into a productive member of society. If I was designing a prison system from scratch then I’d make a system that favors rehabilitation over punishment and that thinks of the 8th Amendment as a human right as apposed to a polite suggestion; “Guilty But Mentally Ill” rulings, Felony Disenfranchisement, Mandatory Minimums for non-violent offences, trying minors as adults, sentencing minors to life imprisonment, involuntary experimentation, and compulsory sterilization would all be Off The Table entirely. Guards who abused prisoners or who “looked the other way” when prisoners to abuse each other would be themselves be arrested and thrown in prison.
The world is full of people who act maliciously and who inflict harm. While it would be wrong to stoop to their level, it would also be wrong to let them go scott-free. If we make rules, but give no consequences for breaking them, then the rules don’t mean anything. Practically, failure to enforce rules (meaning failure to punish those who break the rules) creates a moral hazard (a situation where someone knows he/she will not bare the negative consequences of a behavior, and so engages in that behavior more often).