Is Hillary Clinton being criminally investigated?

That was determined a long time ago when classified information turned up on her server. Those 2 things are mutually “inclusive:” Classified Breach + Unclassified Server = crime. It is simply, IAW 18 U.S. Code § 798, ILLEGAL for this to happen in any way, shape or form:

The Law

Exactly who did what, when and how needs to be “determined” before indictments can be made.