Do I have this right? These two men are neighbors living across the street from one another?
According to the story, the cop's relative was moving in, across the street from the victim, and the cop was helping him move in.
The story itself, is poorly written, though. It is hard enough, attempting to establish a timeline, based on the author's jumping around, and it is nearly impossible to infer any probabilities from it, either.
Although, the most interesting part, was the IAB statement that they take off-duty shootings, "very, very seriously."