ALEXANDRIA, Egypt - In Egypt's second city, medical student Ahmed Nabil lives in fear that the police may come and arrest him any day. As a member of the Muslim Brotherhood, he is part of a movement facing an onslaught by the security forces which toppled Islamist President Mohamed Mursi in July.
"These days we can be picked up at any time," said Nabil, whose parents are also members of the organisation, Egypt's oldest Islamist movement and a supporter of Mursi.
The Brotherhood's discipline and hierarchy helped it win elections after the 2011 popular uprising that ousted autocrat Hosni Mubarak, eventually propelling Mursi into power.
But now the army-led government and its supporters regard the Brotherhood as a terrorist group and enemy of the state. The security forces and police, feared and despised under Mubarak, are lauded for cracking down on the organisation.
The Brotherhood denounces violence and says it is committed to peaceful protest. But as members go into hiding, its key building blocks - local groups of seven members known as usras - are under pressure.
"The most important person for me is the head of my usra," said Nabil. "I get everything from him."
In Nabil's eyes, the usras, which provide everything from Quran studies to marriage counseling, are crumbling. That raises the risk the organisation will fracture, and that some members will abandon peaceful activism to take up arms.
In a sign of how the Brotherhood is retreating, Nabil has bought a new, unregistered mobile phone. He encrypts text messages and is careful about what he writes on Facebook, fearful that the authorities are monitoring communications.
Nabil said he has lost five friends killed in demonstrations and that he narrowly escaped arrest when he took part in a protest. He worries about survival and avoiding jail. The clampdown, he said, could radicalize some members.
This month suspected militants killed six Egyptian soldiers near the Suez Canal, fired rocket propelled grenades at a state satellite station in Cairo and exploded a car bomb near an Egyptian army intelligence building in the city of Ismailia. More than 50 people have been killed and more than 270 wounded in recent clashes between the police and protesters supporting the Muslim Brotherhood.
Even as questions remain over who mounts such attacks, it seems clear the recruitment pool for radicals has grown significantly since Mursi's overthrow.
"Not all people in the opposition can go on resisting peacefully if this unbelievable pressure continues, especially the detentions of leaders who pushed the movement to remain peaceful," said Nabil. Before they were imprisoned, top Brotherhood leaders often told followers that avoiding violence would give the movement the moral high ground against the government.
"All these military actions against us, including killing and torture and arrests, push us to respond with force. One prays that God ends the crisis before we reach the situation in Syria," he said, referring to civil war in that country. "As our grand guide (top leader) said, 'Our peaceful ways are stronger than a bullet.'"
The government makes no distinction between the Brotherhood and al Qaeda-inspired militants based in the Sinai Peninsula who have sharply stepped up attacks against soldiers and police since Mursi was overthrown. The authorities say the Brotherhood's members are terrorists out to spread an Islamic caliphate across several nations, not focus on Egypt's well-being.
A top security official who has monitored the Brotherhood for decades told Reuters: "The usra has been destroyed in a very big way. The Brotherhood member is taught not to think on his own, just to take orders. This is how the group functions. So if there is no one to give them orders it means the group is in trouble."