17 Nathan rang the doorbell and then immediately knocked on the door, without giving the occupants a chance to respond to the doorbell. He was impatient to finish up there so he could focus on the body that had been discovered; he was as aware as anyone in his department that the first twenty-four hours of a murder investigation were the most important. Nathan leant on the doorbell for a second time, making it sound through the house, and was about to knock on the door again when it was snatched open. “What?” the teenage girl who answered the door snapped the question irritably. The annoyance on her face vanished quickly, to be replaced by concern, when she saw the two uniformed constables who stood a short distance behind the man on the doorstep. “Good evening.” Despite the impatience