Yes, Hillary IS the subject of a criminal probe.

The Clinton campaign is busy assuring all who will listen that the ongoing FBI investigation is not a criminal investigation. That is simply not true. According to a source cited by the New York Post the FBI and DOJ do very few civil investigations.

“It’s definitely a criminal probe,” said the source. “I’m not sure why they’re not calling it a criminal probe.
“The DOJ [Department of Justice] and FBI can conduct civil investigations in very limited circumstances,” but that’s not what this is, the source stressed. “In this case, a security violation would lead to criminal charges. Maybe DOJ is trying to protect her campaign.”

According to Makin Delrahim, former chief counsel to the Senate Judiciary Committee, who served as a deputy assistant secretary in the Bush DOJ, “They’re not in the business of providing advisory security services. This is real.”