A son of leading Muslim Brotherhood figure Mahmoud Ghozlan was arrested in 6 October city on the outskirts of Cairo on Saturday.
Yasser Ghozlan, who had LE22,000 in his possession at the time of his arrest, is accused of using the money to fund protests organised by a terrorist group.
He is also accused of joining the outlawed Muslim Brotherhood.
His younger brother Yehia Ghozlan was arrested last week while filming a third detained brother on his way to prison.
Egyptian authorities issued an arrest warrant as well as travel ban last year for Mahmoud Ghozlan, who was formerly the Muslim Brotherhood official spokesperson. He is accused of inciting violence on several occasions after the ousting of president Mohamed Morsi, but has not yet been apprehended by police.