You need to call a criminal defense attorney and speak to them, directly and confidentially, in order to get an accurate estimate. That attorney will need to know your father's criminal record, if he has any, and get some idea of the allegations and what evidence exists. Such discussions are best not held in a public forum like this, but in a one-on-one basis. But no attorney will be able to do more than give you his or her best estimate.
I agree with attorney Smith; additionally his sentence will also depend on who the prosecutor and judge are.... It shouldn't be that way, but personalities and attitudes vary among judges, prosecutors and courts.
Attorney Bonanno's answers to questions are for general purposes only and do not establish an attorney-client relationship. You should carefully consider advice from an attorney hired and who has all facts necessary to properly advise a client, which is why these answers to questions are for general purposes only and do not establish an attorney-client relationship.
I agree with the previous attorneys. For many crimes, there are diversionary programs available that can may allow you to avoid jail time. If he was on probation and already had convictions, chances are he would not be eligible for them. The outcome of his case can depend on many factors including criminal record, victim input and whether or not restitution was made for the property damage, stolen property, etc. You can look up your dad's case on the judicial website and it will tell you specifically what charges he is facing and what class of charge (Class A Misdeameanor, Felony,etc) Each charge would have a minimum or maximum possible sentence. It might be a good idea to meet with an attorney to discuss his options.