I've been following along this thread for a few days and feel strongly about a few things.
1. I believe DV stopped in that Shell station to use drugs. She was there for 20+ minutes with another car, which may or may not have been the friend she was following, or may or may not have been a drug dealer. I can think of very few other reasons she would be parked in a gas station parking lot in the midst of a night of partying for that length of time.
2. I think her friend may have also been a drug user, and that's why he's been so quiet. I bet he was going with DV to also use drugs. He may have been planning to meet up with her later, after circling back to grab her phone, to do the drugs they were buying in that Shell station parking lot. Maybe DV did a little bump to try it out first, and that's what took her so long.
3. I think DV followed a drug dealer/sketchy person in car #3 to go somewhere. More drugs, another party, something. Somewhere along the way, things went south. I think she probably arrived at a location with this person and then something happened that resulted in her being assaulted and/or murdered, or potentially an OD.
4. Potentially LE is deprioritizing this case because DV and friend are drug users and there is no real evidence at this point that harm has been done to her. They may be thinking, well, she followed some guy home to do drugs with him. Until we have evidence that she's been hurt in some way, what are we supposed to do about it? Not saying that's right, but with a heavy caseload, they may be prioritizing others over her.
IMO.