Syria crisis: Concern grows over radicalised Arab-Israelis
2 October 2013 Last updated at 09:40 BST
Hundreds of foreign fighters have poured into Syria from both Arab and European countries, to join the ranks of the opposition.
Many are deeply devout Muslims in their twenties and most join al-Qaeda linked militias, such as the Nusra Front.
Last month, Muayyed Ighbariya became the first known Israeli citizen to become a casualty of Syria's conflict
Yolande Knell meets his father.