It's the usual cliched mix of fiction and non fiction from Kelley. Why so popular? The story still attracts attention - see the "official" web site and here in Lucan, Ontario where it happened.
The book was reset between the second and third printings. Technically this is a new edition, although the text has not changed. The front cover remained the same with only the price rising from 35 cents to 40 in the early 1960s, then 45 and finally 50 cents. The back cover changed only once. The yellow background is a cross on all the printings except the second in August 1954 where it is a large grave marker.
Harlequin 289 first printing - April 1954
Harlequin 289 first printing back
Harlequin 289 second printing back