Due to being accused of being involved in a plan to obtain independence for the Arab people under the protection of England and France, and of inciting the tribes against the Turkish Government, El-Ghusein was arrested by the Government, thrown into prison, and later taken to Aalîya to be tried for political offences. He was acquitted, but the Government disregarded the decisions and escorted him to Erzurum, however he was detained at Diarbekir by its Vali due to the Russian presence preventing them from reaching Erzurum.
Initially he was imprisoned at Diarbekir for twenty-two days, after which he remained at Diarbekir for six and a half months, witnessing and hearing of the atrocities committed by the Turks against the Armenian people. El-Ghusein then fled as described in Seven Pillars of Wisdom, written by the British soldier T. E. Lawrence:
Another friend at court was Faiz el Ghusein, a secretary. He was a Sulut Sheikh from the Hauran, and a former official of the Turkish Government, who had escaped across Armenia during the war, and had eventually reached Miss Gertrude Bell in Basra. She had sent him on to me with a warm recommendation.
Audio recording of Section 3 of Martyred Armenia, by Fa'iz El-Ghusein. The section describes methods of massacre adopted by the Turkish Gendarmes and authorities.
Once El-Ghusein had escape, he undertook to write the book Martyred Armenia, describing it in the foreword as:
[A] service to the cause of truth and of a people oppressed by the Turks, and also, as I have stated at the close, to defend the faith of Islam against the charge of fanaticism which will be brought against it by Europeans. May God guide us in the right way.
The mistreatment of the Armenians in the name of Islam distressed him greatly, and he expressed horror about how his faith was being used to justify the brutality:
Is it right that these imposters, who pretend to be the supports of Islam and the Khilâfat, the protectors of the Moslems, should transgress the command of God, transgress the Koran, the Traditions of the Prophet, and humanity? Truly, they have committed an act at which Islam is revolted, as well as all Moslems and all the peoples of the earth, be they Moslems, Christians, Jews, or idolators. As God lives, it is a shameful deed, the like of which has not been done by any people counting themselves as civilised.