A key scene of the crime: The Bellevue Arms, 1170 Bellevue Avenue, 1927
In 2006: Accordong to the ERBzine website, "...Hickman's bathroom
window is the smallest window on the top to the upper left of
the stone arch. (Dark, with a little white rectangle within the
upper half). His livingroom is hidden by the exterior of the left side
of the building."
Google Street View
Now, undergoing condoization
I've read Michael Newton's Stolen Away
on sopas's recommendation, and besides covering the Marion Parker kidnapping/murder and trial in detail, it also does an superb job of evoking '20s Los Angeles--the way the city moved then, the daily lives of people, the policing, the politics. The city seems motorized and modern, sunny and progressive, while at the same time dark and evil--no less than noirish.
I've also come across a few interesting websites with more details of the case, including the curious presence of Edgar Rice Burroughs (Tarzan and Tarzana) in the story: http://www.erbzine.com/mag17/1767.html
A little more: