After the war, Tehlirian went to Constantinople, where he assassinated Harutian Mgrditichian, who had worked for the Ottoman secret police and helped compile the list of Armenian intellectuals who were deported on 24 April 1915. Meanwhile, Operation Nemesis was being set up to assassinate leaders responsible for the Armenian genocide and Tehlirian's killing of Mgrditichian convinced Nemesis operatives to entrust him with the assassination of Talat Pasha.In mid-1920, the Nemesis organization paid for Tehlirian to travel to the United States, where Garo briefed him that the death sentences pronounced against the major perpetrators had not been carried out, and that the killers continued their anti-Armenian activities from exile. That fall, the Turkish nationalist movement invaded Armenia. Tehlirian received the photographs of seven leading CUP leaders, whose whereabouts Nemesis was tracking, and departed for Europe, going first to Paris. In Geneva, he obtained a visa to go to Berlin as a mechanical engineering student, leaving on 2 December.