If Audrey had her car key in her pants, would it be a surprise if someone who wanted her car ripped her stretchy pants in a struggle for them? She could have been stabbed over the car keys. Maybe at some point the murderer realized Audrey would recognize him, so he killed her. Maybe he didn't go there to kill her, thinking he could get in and out without being caught, but things got out of control. "Young and close". Stupid inexperience and the car theft escalated to murder due to that inexperience and overconfidence?
The strange use of "sexual component" but not "sexual assault" seems more and more like a red herring.