An Egyptian cries as she holds a poster of Mohammed El-Gendy, who protesters say was tortured to death by police last week, during a moment of silence near Tahrir Square, Cairo.

When Egypt's Muslim Brotherhood was formed in the 1920s, it called for social services and a modern Islamic society. In the decades since, it's grown into a modern political force - and seized the reins of power. But now that it is in power the Muslim Brotherhood faces perhaps its greatest test. Al Jazeera's Hoda Abdel-Hamid reports from Cairo.