Recommended reading - The Bloody Spur, by Charles Einstein (1953):

The Bloody Spur

By Charles Einstein.

Filmed as While the City Sleeps (1956), directed by Fritz Lang.

Inspired by the true 1946 case of the Chicago serial killer William Heirens.

Published by Black Curtain Press.
First published 1953.
ISBN-10: 1627551158
ISBN-13: 9781627551151

Description:

HELP ME FOR GOD’S SAKE.
Later the doctors would use these words to decipher the riddle of a perverted killer.
Right now, the lipstick scrawl signaled the start of New York's greatest manhunt.