Police picked up my brother without any cause

Hello my name is Awais Hanif basically I am from Pakistan but currently living in Riyadh Saudi Arabia. I got issue 30 day ago when CID arrested my brother Akbar Ali without any information. After days I got news that they arrest him in robbery case.
I got more information and found that 4 men steal HAVC from Saudi house and she registered case against them. These 4 men also came in camera.
One of them was my brother friend and he have contact with my brother few days ago that the reason CID picked up my brother. Now its been more than 30 days and my brother still in jail without any cause. Please help us we don't know law how work in Saudi