Well even if the perp secretly felt that the victim 'deserved' it, by coming forward immediately, being proactive about reporting the crime, taking full responsibility, apologizing, at least acting remorseful, throwing themselves on the mercy of the court...those are things that can only be helpful to the perp in the end. Of course it totally depends on the nature of the crime, how violent, how much 'planning' went into it, etc, etc.
Most perps believe they can/will get away with their crime. Even the dumb ones, not just the narcissistic ones. Unfortunately, some do get away with it...at least in the criminal system. One can always say that from a soul/karmic standpoint they will never get away with it.