There are various judgments of the Supreme Court as per which a departmental enquiry can be conducted along with the criminal case, unless the proceedings have been stayed by a competent court.
Therefore, as far as I know, if the CBI Inspector (who investigated the case) is officially called for deposing as a witness in the departmental enquiry, he can appear and give his statement in the departmental enquiry without obtaining any permission from the court. This is what is my understanding. After all, he would be deposing only about the factual position as per the investigation conducted by him.
Moreover, when our legal system permits the departmental enquiry being conducted even during the pendency of the criminal case, there should be no objection to the investigating officer deposing in the departmental enquiry even though the criminal case may still be sub-judice.
Dr. Ashok Dhamija is a New Delhi based Supreme Court Advocate and author of law books. Read more about him by clicking here. List of his Forum Replies. List of his other articles. List of his Quora Answers. List of his YouTube Videos.