Let us use the term “victim” in its broadest sense to include anyone affected personally and directly by an act of violence. It is as human as human can be for a victim to desire vengeance. However, this is precisely why we in the United States do not allow victims to sit on juries empaneled to judge those who commit acts of violence. The society's interests are different than those of the victim.
Now if the society as a whole has an interest in committing acts of violence, the death penalty does well in that regard. However, I recommend that before any thinking person advocate the ultimate act of violence as a valid and positive societal interest they read Albert Camus's brilliant essay on the death penalty entitled “Reflections on the Guillotine” in Resistance, Rebellion and Death: Essays.
Victims who advocate that society as a whole ought to commit the ultimate act of violence in order to satisfy the victims' own personal, human desire for vengeance display a sort of lack of personal courage. If the victim desires vengeance so much, then the victim ought to find the balls to take that vengeance themselves and willingly bear the consequences for so doing rather than ask that the rest of us do it for them.
If someone rapes your daughter violently, then find a way to kill him yourself if you must. I for one would applaud the personal integrity of that course of action. However, please do not ask me to do it for you.