Authorities said the car rental company got an anonymous call saying their car could be found in the alley at Jefferson Boulevard and 12th Avenue. When an employee went to retrieve the car at about 1 a.m., he found that body.
The woman's identity was withheld pending notification of next of kin.
Homicide detectives are handling the investigation.
Anyone with information is urged to call the LAPD Southwest Station at (213) 485-2582.