Hello
I'm from France near Paris and I discovered this website after seeing Mulholland Drive, my favourite film! And this website is excellent! The mention about the black Dahlia's murder as a source of inspiration that might have influenced the MD pilot remembered me another murder : it was in 1969 on Cielo drive and the victim was actress (and Polanski's wife) Sharon Tate.

Maybe it's just coincidences but (extracts from 'Helter Skelter'):

• "At 0914 hours, West Los Angeles Units 8L5 and 8L62 were given a radio call, 'Code 2, possible homicide, 10050 Cielo Drive'. The units were one-man patrol cars. Officer (Lt?) Jerry DeRosa, driving 8L5, arrived first, light flashing and siren blaring." => In MD, Apt #17 where lies the corpse is 'L.J. DeRosa'.
• "Officers Whisenhunt and Burbridge came next (...) Those windows along the front of the house : behind any a killer could be waiting, watching. Leaving DeRosa on the lawn, Whisenhunt and Burbridge went back toward the north end of the residence, looking for another way to get in. They'd be open targets if they entered the front door (...) They found a window open on the side (...) They climbed in. DeRosa waited until he saw them inside the house, then approached the front door (...) The door being open, inward, DeRosa was on the porch (...) => In MD, Betty found a window open on the side, she climbed in, Rita was waiting until the front door being opened.
• "Not until they were almost to the couch did they see what was on the other side. She was young, blond, very pregnant. She lay on her left side, directly in front of the couch, her legs tucked up toward her stomach in a fetal position." => in MD, the corpse of the blond woman lay on her left side, in fetal position.
• Sharon Tate was in the film "Valley of the Dolls" about the Jennifer North story => in MD, the Sylvia North story.
• 10050 Cielo Dr. was a "fairy-tale-style" property, it was occupied by french actress Michèle Morgan during WWII, before Polanski rented it => in MD, Lynch choose for Sierra Bonita a complex, which consists of eight small, wood-shingled bungalows built around a central courtyard. The bungalows were once occupied by Walt Disney Studios animators and the storybook-like architecture served as the inspiration for the Seven Dwarf’s cottage in 1937’s Snow White and the Seven Dwarfs.

I think it's likely that the Sharon Tate murder was one of a myriad inspirations for Lynch. He seems to pull from a vast library of symbols, thought patterns, pop culture references, etc. Of course, we all know this, just stating the obvious I guess ;)

Cool post though, and if you see the crime scene photos from the Tate murders (not that most people would want to look at such a thing) you do see some similarities between her body and the corpse at Sierra Bonita. Maybe intentional, or maybe even an unconscious thing by Lynch.