I get it. The objective is to take the evidence, or facts of the case, and find some alternate explanation. The green truck is of no interest to police ... perhaps a diversion. The 4x4 fence posts are not fence posts, they're part of an invisible gate that is big enough for a vehicle to drive through. It's easier for a criminal to remove a section of a fence and drive a vehicle onto the back lawn than to remove bodies from a crime scene via a door ... except, perhaps the bodies weren't removed. Perhaps the bodies are still at the crime scene. Maybe someone, not the chemist from Airdrie, but someone else with soap making materials, made the bodies disappear in Parkhill. When the homeowners move into the Parkhill house, maybe they'll find the bodies.