You can act as your father's advocate (as long as you are over 18 years old). Our country's law stipulates that the following persons can serve as defenders for criminal suspects: lawyers and close relatives. If these two do not exist, the case handling agency can also designate personnel from the unit (or sub-district office) to defend them.
Defense means that during the trial stage of the case (that is, when the case is transferred to the court), you should go to the court in time to complete the entrustment procedures. After that, you can review the file materials and make suggestions that are favorable to you based on the law and facts. Father's defense.