Also;
And; Her mom said earlier that SS was "very intoxicated". Most folks aren't fine and coherent, when they are very intoxicated (then again, maybe my interpretation of very intoxicated is different than her mom's). It was also reported, in the beginning, that there was another girl in the car too, could be that the one guy's hair is long? Was there another female who left the house earlier and confirmed she was there? It's all so strange, that I think that early on, some believed, that she just took off, and would show up after awhile.
I think she and the friend got mad, she chose to not ride home with her, and got a lil lit, and still wanted to have some fun. Had struck up a convo with one of the guys at the bar, and decided to head out with him for an "after party". IF she was a former heavy user, or even a casual user, and she used hard drugs that night, combine that with alcohol, and her body not fully healed, it could have been a fatal mix, and it's just a matter of finding her. That's most folks' guess around here.
The boys may know that she left the home, with one of the them, that morning, but are covering for that one, also. She may have been out of it, and died later that day, somewhere else. They had to get her out of the home before the parents came home?
Just spitballing.