As far as the justice system goes, the probation officer can file a notice of violation with the court, if he/she thinks you have violated the terms of your probation. Usually, by this point though the probation officer has used his/her discretion to warn you off the record about the possible violation and warn you that the next time they will inform the court. If the PO does file notice with the court, the judge will either issue a show cause summons ordering you to appear in court or a bench warrant for your arrest so you can appear before him/her for a show cause hearing (depending on the severity of the charge you are on probation for and/or the nature of the alleged violation). At that hearing the probation officer and/or prosecutor has to show to the judge's satisfaction that you have violated your probation. You have a right to be represented by counsel and rebut the state's case against you. The standard of evidence by which you are judged may no longer be "beyond a reasonable doubt," but "preponderence of the evidence," but you still do have the due process right to present your case. If you are found to have violated probation, the sanction could range anywhere from having to serve your full sentence, extended probation or tighter conditions.
Parole is different from probation. Parole is an administrative determination emanating from executive authority. A parole officer has the right to arrest you and take you straight back to the penitentiary and your fate is determined by the state parole board not the court, which is usually appointed by the Governor.
The procedures vary from state to state, but that is generally how it works.
PAC's problem is that he not only has to answer to the justice system, but also to the commissioner, who can do whatever he wants as far as suspending him based on whatever standard of evidence he wants to use.