Based on my own experience working at a convenience store (and being robbed while working there), I keep thinking about a few things - forgive me if I got some of this wrong, since I'm relatively new to this case -
the front door of the store was unlocked still,
the register drawer was open,
the back door was open and/or had some signs of her blood outside it
Okay well when I was in her situation, I basically looked up and saw two guys come in wearing camo and one held out a gun. I assumed right away that we were being robbed, because that's what people with guns DO at convenience stores.
I keep thinking it could be pretty simple -
the front door was unlocked because it was still business hours
the cash register was open because she saw a guy come in with a gun or something threatening and assumed she was being robbed, so opened it in preparation for handing over the cash
the back door was open and/or some of her blood was found out there because he somehow let her know that he wasn't there for the money but rather for her, and she bolted out the back upon realizing that fact, or he took her out that way or something
Any reason these can't be possible scenarios? Like I said, I'm relatively new to this case, so may have things wrong or otherwise have a fundamental misunderstanding that messes up these thoughts.