Kesinovic and Selimovic were both children of Bosnian refugees who fled to Austria from the war in their country during the nineties.
Their families reported them missing after they disappeared from their homes in Vienna last year.
They reportedly left a note for their families which read: “Don’t look for us. We will serve Allah and we will die for him.”
They were traced as taking a flight to the Turkish capital of Ankara, and travelling on to the region of Adana, close to the border with Syria.
It emerged they had joined Isil after Kesinovic telephoned her sister from Syria to let her know she was alright.
She reportedly wrote home late last year telling family she wanted to return and that she has had enough of the extreme violence she witnessed every day.