Muslim Brotherhood leading member Essam El-Erian, who was serving various jail terms in prison, has died from heart attack following a quarrel with another detained brotherhood member over the current situation of the terrorist-designated group, informed sources said on Thursday. "El-Erian was conducting a discussion with one of the leading members of the Brotherhood about the current situation of the group and its future plans before a quarrel erupted between the two which caused him to suffer from a heart attack, leading to his death," the sources added. El-Erian had been sentenced to life imprisonment, along with 10 others, in a terrorism-related case over storming the country's eastern borders. He was also given another 20 years in prison over violence that took place outside Ittihadia presidential palace in December 2012. He was sentenced to death over violence-related offences during the dispersal of the Rabea sit-in in August 2013, a verdict that was appealed by his defense.