We've been chasing, prosecuting and jailing old Nazis for decades. Continental Europe yawns and anti-Semitism creeps steadily upward, year after year. Are these cases worth the effort? I think they are, but it's more about going on record about who we are and what we believe.
We can't count on any measurable deterrence factor, people who would commit those vile acts are predisposed to ignore such factors. In the old days when pickpockets were hanged in the town square, other pickpockets often worked the assembled crowd.
Nonetheless, we have to do what is right. We need to bring wrong-doers to justice, particularly those that do things of this sort.
That others will do the same in the future, regardless of our punishment of past perpetrators, is of no consequence to us - THEY are guilty of what they do, not us. But if we turn away, then we are guilty of indifference to some of the most hideous crimes ever committed. I can’t live with that.