Well, a little bit of research seems to suggest that an investigating officer has the weight of the US government behind him, and if the situation points in the direction of phone calls or emails, they can subpoena all of that. I guess you learn something new every day.

So she's going to be forced to choose:
a) Try to lie through everything. Get caught in a lie, get a dishonorable discharge.
b) Admit to everything. Take your lumps, but probably not a dishonorable discharge.