I wish I could sit on the fence with you,
@Inthedetails--but there are two big things that just prevent me from being able to believe she is missing of her own volition.
The first is that she has a young baby, and it just seems...unlikely...that she would leave without the child. Now, is it possible that maybe she felt the baby would be at risk while she fled, or she hadn't really wanted to have a child in the first place, or she honestly believed the child would be safer/better provided-for (temporarily or long-term) if in the care of its father? Of course! But just going by the cases I've followed, it would be a pretty unusual circumstance for a new mother to abandon her infant without a word to anyone about it.
Second: she had an INS interview coming up that she apparently just missed. I hope anyone who's more knowledgeable about this than me will weigh in, but I believe it can take a while for a person to even get an interview slot--so it would seem to follow that most people don't miss those appointments without a very, very good reason (and if they know they are going to miss it, I would think most people would at least attempt to officially cancel the appointment so as to not look irresponsible/careless/negligent to the agency which dictates their visa/citizenship status!).