How to find a missing person?

Good day,

My workmate was missing 2 days now. We track his flat and check his whereabouts and found out he was last seen at a billiards place near his house.

Two guys from the billiards place informed us that he and 3 more (2 guys and 1 lady) was taken by the CID. We went through the police station in Al Murraqabat and the police there said that his name is clear and he is not detained or jailed.

How can we find him now?