I'm assuming "no sign of foul play" means no obvious injuries to her body.
The guesses upthread about the Matrix drugs seem pretty right on, to me. I hope they get hold of that "friend" she met on Sand Hill Road, before she lost track of her car. Sand Hill runs from El Camino Real past the border of Stanford (near the medical center) up through a high tech industrial park area (where SLAC/linear accelerator is) but then turns into a rural road with expensive homes, and heads toward Portola Valley/Woodside (where there are still living hold-outs from the Grateful Dead era, complete with boutique drug sales, IME).
I would be very curious to know whether Erin had a prescription for any type of sleep aid. Lots of people who travel internationally, as she did, have such an Rx, but combined with other drugs, it can be dangerous. Surely Erin was not exactly thrilled about sleeping in her car (which speaks a lot to her level of confusion, she could have gone to a nearby hotel). It seems she may not have been able to figure out how to charge her phone? If the car was completely out of gas, that explains that. I first thought she sounded manic (due to husband's info) but a manic person would most likely get out of the car and walk the short distance to a gas station or at least approach total strangers to ask for gas. Of course, manic people can crash rather suddenly, too.
Whole incident is truly bizarre and I'm guessing we won't know much more until the toxicology report is released. If it's negative and they don't find evidence of some major disease process (which to me seems far-fetched, as it would have had to have very sudden onset), this will be one of those really strange unexplained deaths. Heart attack is always possible when under stress, but she was so young. Still, if she underwent a lot of weight loss quickly, it's also a possibility.
Thanks again
@PommyMommy for updated timeline on EV case.
Following the facts for this case, EV was scheduled to go home to Utah on Monday, departing from SJC on early evening flight. EV's first reported signs of something seemingly off with her begin on Monday around 3:30pm -- i.e., contact with mother when EV can't locate parked rental car.
Next, EV presents "textbook manic" to her husband in subsequent phone calls. Phone evidence indicates EV's phone was moving around San Jose area during the hours she should have been aboard flight to SLC. Husband confirms EV also did not return the rental car to Hertz.
Reportedly, EV's unusual behavior to her family beginning around 3:30pm - 10pm, and missed flight home, is concerning enough that husband requested SJPD Officer contact EV directly.
Officer called EV's phone number, and she answered the phone. I'm pretty sure Officer didn't chat about the weather, or Monday night football, but asked enough questions to ascertain that EV was not being held against her will, and not a victim of crime.
It appears EV did not provide Officer with her location, and did not request or accept offer for assistance, but instead told Officer that "she was with friends."
For reasons unknown, husband never publicly reported that EV told Officer she was with friends, only that she sounded nonsensical.
After EV was located deceased, SJPD released information about their investigation. Following phone call with EV -- Officer reportedly attempted to locate EV to both confirm she was "with friends" under her own power, and not in need of medical assistance, using the most recent phone pings provided by Verizon which were reported as Menlo Drive north of Almaden Expressway.
Officers searched the area, as well as local hospitals,”over the course of several hours.” Police said they also searched streets further north, where EV’s phone pinged a few more times before shutting off.
Without evidence to suggest EV being driven around town by other that parked the vehicle on the street and left EV alone in the vehicle, seems evident that EV was cognizant enough to drive around for hours, and finally park the vehicle on the street -- presumably on Monday night.
Police have also reported there's no evidence of foul play in EV's death.
Unknowns:
Reportedly, the person EV met with on Sand Hill (before she contacted mother at 3:30pm looking for parked vehicle) has been cooperating with family and investigators. Nothing publicly available from the party that last met/saw EV in person. Unknown if they shared a meal, drinks, or where meeting occurred.
I think it will be details from that final, live meeting with EV that will provide the clues what happened to her in her last hours leading to her death.
Also believe preliminary autopsy reports are complete, but toxicology results required to confirm COD.
If this was a death from a medical event, I believe family would have announced preliminary results already.
I think we will later learn EV's death was drug related, accidental or otherwise.
MOO