People die all the time; some from purely natural causes, some by acts of random, accidental violence and a few by another individual's deliberate choice. In the city of Rushborough, people were dying violently and nobody knew the cause. Worse, those deaths were so horrible that the fear of meeting the killer exceeded vastly the remote chance of falling victim to ... whatever it was.
At such times, the public demands action and the public voice is amplified and distorted by the news media. Every expert knows exactly what to do but few can reach agreement on common ground. Each joins battle with the others for media attention and personal publicity.
The police, charged with taking action but lacking the information needed to direct that action, are forced onto the defensive. While the media are busy erecting hoops and demanding that the police jump through them, the investigation carries on in an increasingly corrosive atmosphere.
At such times, enthusiasm runs dry as those involved in tracking down a minor threat to public safety, in real terms, begin to ask whether they are receiving a fair reward for all their effort.
When any given individual has more chance of being struck by lightning than of falling victim to the mysterious killer, and when those involved in the incomplete and therefore unsuccessful operation suffer professional assassination, they might just start thinking that the time has come to think of number one and run for cover.
So who finds the killer then?