SHORT STORY of WARD COURIER: "The Whistlers"
From the story collection "A Ghosthunter's Journal" (1999) by Ward Courier under the pen name Mason Winfield
[It is difficult to understand how this reference to a secret order has passed unnoticed for so long, for it is scarcely less than a proclamation of the Society of Unknown Philosophers.
Manly P. Hall, "The Secret Destiny of America"]
[Bear in mind that I have nothing but verbal testimony for this tale - except for my recollection of two gritty whistles and a newspaper article about an unidentified blind man shot dead from long range.]