On the morning of 30 May Prvanović's revenue sergeants assembled and Sergeant Budivoj Grbić accepted the task and led Princip and Grabež by foot to Isaković's Island, a small island in the middle of the Drina River that separated Serbia from Bosnia. They and their weapons reached the island on 31 May. Grbić passed the terrorists and their weapons to the agents of the Serbian Narodna Odbrana for transport into Austro-Hungarian territory and from safe-house to safe-house. Princip and Grabež crossed into Austria-Hungary on the evening of 1 June. Princip and Grabež and the weapons were passed from agent to agent until on 3 June they arrived in Tuzla. They left the weapons in the hands of the Narodna Odbrana agent Miško Jovanović and rejoined Čabrinović.