Proof of innocence in an embezzlement case

My brother in law is in jail for taking AED 12 million from his company and he is in jail (Abu Dhabi, UAE) under remand.

I don't know whether he had taken the money or not, but his employer is saying he had taken it and given him a confession letter. I don't know about the confession they took.

I had not seen him because it happened last week and I am not able to go and meet him as it is very far from my house and also I have no blood relation.

 I need to take permit from the prosecution department. I trying to meet him by next week. Kindly advise me what I need to do. Also, advise me on:

1. Suppose the above thing has happened, how many years he needs to be in jail?

2. If it is a false case by the employer, how will we prove his innocence?

3. Will the court give a chance to him to prove he is innocent and how? Please note that he has no advocate.

4. I assume this will be a false case as the employer is saying he started doing so for the last three years. This company had every year annual audit and they did not find.