I hope LE has checked them out, too. Sometimes kinda hard to believe they are on top of this case.
It's stretch for me to think Ricci is involved (I know, I could be wrong), it just doesn't fit his M.O. criminal history.
It DOES fit the M.O. of an awful lot of child snatchers of late and in past years -- a loner type, insecure, not especially random or impromptu.
An alternate, though less firm theory, is that it is someone who perhaps perceived (rightly or wrongly) that Elizabeth was having personal problems and wanted to take her away from those problems.