The reason I don't think anyone else is involved is because she is very protected behind bars and in police custody. More so than being out and about. That would be the perfect time for her to point fingers and get them behind bars so that she can go free.
Also remember, the more people involved in a crime, the higher the chance that someone will talk and spill the beans. So far, no one has come fwd to claim the $225K reward and no one has given LE any other persons of interest to investigate.
Could just be coincidence that her friends moved away. None of which moved to another country (I don't think) which would be what some guilty parties would do in order to avoid extridition.