Read an article yesterday that said that the home owner had bought a laptop and some other items from the girl a few days prior to the shooting. She claimed she was trying to earn bail money for her boyfriend. The next day she went back to talk to the homeowner, this time asking him to loan her the money for bail. The day after that she was shot dead outside of the home by either the two guys with her (the ones charged) or one of the 5 people in the home (none of which were the homeowner she'd previously interacted with).
My guess is drugs, honestly.