John became patriarch during the rule of the Ikhshidid governor Muhammad Ismail ibn al-Sanaji in Jerusalem.
In 966, after having complained several times, Muhammad took revenge on John by stirring up the Muslim mobs against the patriarch.
The mob descended on the Church of the Holy Sepulchre, set it on fire, and caused its cupola to collapse.
The next day the mob continued its reign of destruction during which they found John hiding in the oil cistern of the Church of the Holy Sepulchre, and murdered him.
[2] A second version of his martyrdom maintains John was burned at the stake by a Muslim mob after writing to the Byzantine Emperor Nikephoros II Phokas, pleading with him to hasten to Palestine and retake it from the Fatimid caliphs; however, Nikephoros did not take control of Palestine until the 970s.