Myria: I'd run, too, if I were facing a really long prison sentence.

Let's say he didn't do anything else bad after the three rapes - what's the point in imprisoning him now?  It's not like rehabilitation would be required.

Well, only if you think that the "point' of laws are to punish and imprison the actual offender, and not, for instance, to assure the community at large that the rule of law is in fact enforced. It's a true and statistically and empirically proven fact, for instance, that the majority of murderers only commit one murder; if they are not caught (and punished) they're not going to commit another murder ever again. John List is an obvious example: He murdered his entire family one day, and was found something like 35 years later (with another whole family) having never acquired so much as a parking ticket in the meantime. Another guy in Southern California killed two cops after kidnapping four teenagers and raping one of them; he was found so many years later that he was a great-grandfather and the rape victim was in her 80's. He also had not reoffended in all that time.

Shall we say, Oh, well, then, no harm no foul? These guys are clearly no threat to society so let's just overlook the fact that they killed people a long time ago? I guess we could--if the only purpose of laws is to punish the offender. However, laws are also meant to stabilize society and assure the community that justice is a concrete thing and not merely an abstract concept. Laws and the guarantee of their execution--even after many years and no further offense--is what keeps people from taking justice into their own hands; the assurance that the authorities have things under control.