If they do, who is likely to know better than the girl?
And its not just a matter of honor-killing; she apparently believed she would be removed to her parents' homeland, and then married off against her will. Again, a good reason to run.
What kind of evidence would constitute credible evidence? The fact that it happens isn't sufficient? Does anyone think the parents would tell the State of Indiana that, yes, we're taking her home to get her away from bad influences, and we'll be marrying her to a good muslim man...? Did anyone expect they would say that?
She's almost eighteen. She's made her decision. If this drags out for any time at all it will be moot.