Reading through this...the driver is extremely sketchy. The idea that he "unbuttoned her pants to help her breathe" is just ridiculous. And it doesn't sound like they were just unbuttoned but pulled down. Who on earth would unbutton someone's pants while they were having a seizure? Not to mention the semen-like stains on her pants. I didn't see in the transcribed police files earlier in the thread that they were tested or confirmed to be semen but coupled with the undone pants and exposed breast, I think we can surmise.
Giving him the benefit of the doubt, maybe they were having sex when she overdosed and he didn't want his baby mama back home to find out so he dumped her. Maybe she was selling sex to him in exchange for drugs (or maybe that's the reason he picked her up in the first place) and then overdosed so he dumped her to avoid prostitution charges and so his baby mama wouldn't find out. Obviously in both of these cases he is still scum for not taking her to a hospital or properly rendering care. It sounds like he did call 911 but didn't actually communicate what was going on. Maybe he was using a payphone behind the strip mall and saw someone coming so he hung up?
Worst case scenario is he was sexually assaulting her before, during or after she overdosed. Maybe he laced her drugs with something. Do we even know for sure there was a third party drug dealer involved? The driver claims the dealer was there while she overdosed but even if he exists, he may have just sold them the drugs and then left. I suppose if the cocaine was laced, it would have shown up in the toxicology. Plus the ME confirmed there was enough cocaine to be fatal. But regardless there seems to be plenty of circumstantial evidence the driver was engaging is some sort of sexual activity with her. Then he fled to Mexico once the police tracked him down. All sketchy.
I also agree with the conjecture she was an undocumented immigrant. Or at least her family was. That would discourage them from identifying her to the police even if they saw that she was a jane doe. Terribly sad but that's reality for undocumented immigrants here.
Hopefully she can be tracked down through DNA evidence. And if she is and her family is still here, undocumented, I hope they don't face any deportations or harassment. And hopefully the police can get back in contact with the driver and try to push him for more information about what really happened.