Justice perverted - Kevin Barry New Yorker story

In current New Yorker, a story by Kevin Barry, Death Song Ox Mountain?, set in rural Ireland about a feckless cop out of shape and soon to retire who fixes his sites on capturing an evil scourge who is a serial brute toward women. The story told in short scenes some overly lyrical others straightforward and almost hard-boiled covers material that others might treat in an entire novel - a story that's a marvel of precision. In just a few hundred words Berry creates a vivid portrait of this pathetic, wheezing cop and his final effort to rid his small world of evil and violence - and also a portrait of this nasty young man. The story has several twists, notably a scene in which the copy interviews one of the man's victims, perhaps his last victim, an uncouth, drunk woman - a scene that could have been dripping in sentiment and unearned sympathy but that instead is very tough and unpleasant - we can see that the evil guy finds victims perhaps much like him - but we still want him to get justice. Strangely, we also learn that the young scourge is dying of cancer - not sure why this fact has such presence in the story, but knowing of the fatal illness makes us want the cop to just leave the guy on his own to die - and yet - he can't, and doesn't. In the last scenes, the cop tracks the guy down to a hiding place in the mountains, captures him, and then - an a scene conveyed more by indirection than by straight-on description - the cop pushes the guy off the mountainside to his death. The cop accomplishes his ends, but at what moral cost? And then, in a final section, we understand that the evil guy has left his progeny all over the county - evil procreates - and the cop, in that sense, accomplishes nothing but becomes complicit in a perversion of justice: he himself his "died."