One last avenue of diplomacy and investigation lay open. The lone legal adult amongst the armed assassins was Mehmed Mehmedbašić.
Following the assassination, Mehmedbašić fled to Montenegro where he was arrested by the police. In Montenegrin custody, Mehmedbašić confessed to a wider conspiracy including an irredentist Serb terrorist planning meeting in Toulouse, France. Learning of the arrest but not of the confession, Austria-Hungary asked Montenegro to honor their mutual extradition treaty and hand over the assassin. After Montenegro shared Mehmedbašić’s confession with the French Ambassador, the problem of extradition was solved by permitting Mehmedbašić to “escape” to Serbia.