I can't come up with a scenario of her being specifically targeted since they've cleared the husband. If she was targeted by someone who knew her morning schedule, I don't think it's likely that she'd get to the point of being able to text someone about leaving her ID at home, then having to go home and get it. I mean, that would completely disrupt a pre-meditated plan if there was one, right? The whole plan would have been thrown off.
The husband was cleared, and it doesn't make sense that it would be someone else she knew (i.e. if she was having an affair or something), because of the whole ID badge thing. It WAS found out home, so that text was truthful, right? So that leaves a stranger/crime of opportunity.
Or suicide (which I'm leaning away from now, although it was my initial thought)