Mohamed Ahmed Hassanein, also known as Hamam el-Kamouny, was sentenced to death by an Egyptian state security court on Sunday for his part in the 2010 killing of Coptic Christians.
Two other defendants accused of aiding Hassanein in the killings are due to be sentenced on February 20.
The sentence comes amid widespread anger among Copts who feel that the government is not doing enough to protect them.
Much of the resentment centers on the lengthy process in bringing the accused to trial. For a year, court proceedings against the three Muslim men were postponed numerous times. The U.S. Commission on International Religious Freedom denounced the delays to the trial and to convicting the men.