@gungasnake,
My guess is that she was trying to hide that she was living alone from the school. I think if she had talked to them they probably would have found a way to work with her to avoid reporting her as truant.
Most likely she was afraid that she and her sister would be placed in separate foster homes and hid the fact that she was in such dire circumstances. Hopefully now that everything is out in the open things will get better for her.
I've already heard that the judge had been approached about erasing her record and that he is considering it so that's good.