A brother is arrested in the UAE. What to do while being in home country?

Dear sir/madam,

My brother was arrested about 3 weeks ago because his visa was due and he overstayed. Since then, I haven't heard from him, his lines are switched off.

The people who got arrested together with him have since then been deported to Nigeria, but he is yet to return. There are no other offenses except for overstaying.

What can I do?

I look forward to your reply,

Thank you!