NAHIA, Egypt — Abboud al-Zomor — the former intelligence officer who supplied the bullets that killed President Anwar el-Sadat and is Egypt’s most notorious newly released prisoner — waxes enthusiastic about ending the violent jihad he once led.

“The ballot boxes will decide who will win at the end of the day,” Mr. Zomor said during an interview in his large family compound in this hamlet on Cairo’s western edge. “There is no longer any need for me to use violence against those who gave us our freedom and allowed us to be part of political life.”

In its drive to create a perfect Islamic state, his Islamic Group and other groups like it were once synonymous with some of the bloodiest terrorist attacks in Egypt. But they are now leaping aboard the democracy bandwagon, alarming those who believe that religious radicals are seeking to put in place strict Islamic law through ballots.

The public approval of the constitutional amendments on March 19 provided an early example of Islamist political muscle, the victory achieved in no small part by framing the yes vote as a religious duty. But perhaps the most surprising aspect of the Islamist campaign was the energy invested by religious organizations that once damned the democratic process as a Western, infidel innovation masterminded to undermine God’s laws.