Yes, there was some speculation that maybe the body of a woman found on Plum Island not too long ago was related, but it does not appear there was any relation. I don't remember the particulars, but I think she was middle aged and childless.
The lack of people coming forward (if it was indeed an accident or some health issue and not murder), doesn't make sense unless she was the child of illegal immigrants, or her parents/guardians were involved in something nefarious. If she was the daughter of a runaway/young single mom who was kidnapped, I still think someone would ahve come forward and reported the mom and daughter as missing by now. The mom would have to have had a job/childcare, and if she didn't, she would have had to live with someone and gotten benefits...