The second to last paragraph especially emphasizes the policeman's remorse over what he's done to the elephant and draws the reader into this guilt. He cannot even stay to watch it die after he's unloaded several rounds from two guns into the dying beast and they have not ended it. He wants to feel guiltless about shooting the elephant, but he knows that he ought not to have done it out of pressure for being a good "sahib". This paragraph lets the reader know that the animal did in fact suffer, a lot, and the natives cared only for what the elephant was worth to them dead having stripped it by late afternoon. It took the poor animal a half an hour to finally breath its last breath and the shooter feels awful about it. The whole reason he shot the elephant was look good in front of the natives and he is not a thought to them after the elephant is dead. This paragraph draws the reader into the guilt by letting us know how severely the animal suffered and how the natives didn't care and he was forgotten to them after the animal died.
Varying the length of paragraphs, just like varying sentence length or structure, provides a way to achieve effect. A short paragraph can isolate a powerful idea for emphasis or drama, it might communicate tone, and it might also act as a means of transition. The third last paragraph ends with very dramatic and powerful detail of the animal’s death. The brevity of the second last paragraph enables the power of an understatement. On the one hand, it is cursory, to the point. The action is done, the animal dead, so the narrator tersely tells us he walked away. But the story doesn’t end there, for more gory details follow: the animal is stripped to the bones. He communicates a tone that shows his disgust with himself and what he did; he suggests he wants to be rid of the topic—he doesn’t want to talk about it anymore. But very dramatically he describes the result of his action, which is even more violent than the actual deed. The brevity enables all of this to stand out in relief to what precedes it. The paragraph also provides transition to the conclusion, which is the aftermath, where again the narrator expresses contempt for himself, especially in the last sentence.