Egypt deported on Friday a German citizen on suspicion of terrorism, authorities said. The 23-year-old Goettingen resident was arrested at Cairo airport on December 27 and repatriated Friday on an early morning flight to Frankfurt after being questioned by police, Cairo airport officials said, according to The Associated Press. Security officials said interrogations revealed the German of Egyptian origin believed in the extremist ideology of the ISIS terror group. Another detained German, an 18-year-old from Giessen, is still in custody. He was stopped at Luxor airport on December 17 and authorities also accuse him of supporting ISIS ideology that advocates terrorism. Christofer Burger, a Foreign Ministry spokesman, told reporters in Berlin that Egyptian authorities confirmed the Giessen resident is in their custody, but that the German embassy had not yet been granted consular access to him. "All we have received from the authorities is the confirmation that he is in custody," he said. German media have reported that both young men had been on trips intending to visit their grandparents. Egypts Supreme State Security Prosecution is now leading an investigation into the men, reported the AP.