How does Nick interpret or explain the events that lead up to Gatsby's death in The Great Gatsby?
As Fitzgerald's narrator, Nick has two roles. He recounts the events of the narrative, beginning with his arrival in West Egg in the summer of 1922 and ending with his last night there. The second role he plays is to interpret those events. Through Nick's reactions and final judgments, Fitzgerald imposes a sense of morality upon the story.
When the novel opens, Nick is back in the Midwest, still dwelling upon what he had seen and experienced in the East. He makes it clear immediately in the first chapter that he had developed an admiration and fondness for Gatsby, despite some aspects of his character. He refers enigmatically to "the foul dust" that "floated in the wake of his dreams." He also says that something "preyed" upon Gatsby.
By the conclusion of the novel, we understand that these references refer to Tom and Daisy Buchanan. Nick blames them for Gatsby's death, seeing them as "careless people" who go through life destroying others through their arrogance, irresponsibility, and selfishness, then retreating into the security and comfort of their wealthy lives. The Buchanans are amoral people.
Nick also makes it clear that Gatsby's death resulted, in part, from his own romantic nature--his inability to abandon the dream he had lived with for years. He was naive and unrealistic, unable to recognize truth. It was Gatsby's romantic innocence that made Gatsby prey, unable to recognize predators.