CAIRO — An Egyptian man accused of supporting the Islamic State was sentenced to death on Saturday in the fatal stabbing of an 82-year-old Christian doctor in Cairo.

Prosecutors said the killing in September 2017 happened when the 40-year-old defendant requested to see the doctor, pretending to be a patient.

The man, who was not identified, started stabbing the doctor when he was shown into the clinic’s examination room, and then stabbed the physician’s assistant as she intervened to try to stop the attack, officials said.

Prosecutors said the defendant had embraced the extremist ideology of the Islamic State. The local affiliate of the group has targeted Egypt’s minority Christian population as punishment for its support of President Abdel Fattah el-Sisi, who has cracked down on Muslim groups since taking power after the military ouster of President Mohamed Morsi in 2013.