Jamal Khashoggi's murder happened in the Saudi Arabia embassy in Turkey. President Erdogan wants the 15 men suspects to be tried in Turkey. Is that possible?
Saudi Arabia and Turkey have no extradition treaty (Source). It's possible, however very unlikely, that an ad hoc arrangement could be made between the two parties for only this case. Recently, such an agreement was used to extradite people accused of war crimes from the UK to Rwanda.
There is one agreement (31/05/1930) listed in the judicial agreements (only available in Turkish), however it doesn't state anything about extradition.
On the other hand, Turkish sources report that Saudi Arabia extradited 4 suspects in 2017.
Almanya ve Gürcistan’dan 12’şer isim, Türkiye’nin talebi üzerine iade edildi. Almanya ve Gürcistan’ı 5 suçlu iadesiyle Azerbaycan, 4’er iadeyle ise Bulgaristan, KKTC, Suudi Arabistan ve Ukrayna izledi.