The family of Ibrahim Halawa have revealed their anguish as he continues to be held in an Egyptian prison, six months after his arrest.
The 17-year-old son of Ireland's most senior Muslim cleric, Sheikh Hussein Halawa, was arrested in Cairo last August, alongside his sisters Somaia (28), Omaima (21) and Fatima (23).
Ibrahim's sisters were released on November 15 last year.
However, Ibrahim's detention period has been extended a number of times.
"They don't know the reason why they are keeping him this long," Somaia told the Irish Independent.
Ibrahim's friends yesterday organised a protest outside the Department of Foreign Affairs in Dublin to "get the Irish Government to try and do more and take more action, to push more and ask for his release".
Somaia and the entire Halawa family are becoming increasingly concerned about Ibrahim's state of mind and the fact that he is being kept in an adult prison.
A decision on whether the authorities will release Ibrahim Halawa or continue his detention will be made at a hearing on Tuesday in Cairo.
According to Somaia, while her release alongside her sisters in November was a huge relief, their brother's continuing ordeal is "very upsetting" for her family, particularly her father who is Imam of the Islamic Cultural Centre in Clonskeagh, Dublin.
The siblings were detained after they sought refuge at the al-Fath Mosque in Cairo, when a day of protest against the ousting of President Mohammed Morsi called by the Muslim Brotherhood turned violent.
Some members of the Halawa family have stayed on in Egypt and have been working over the past six months with lawyers in Cairo to secure the release of Ibrahim.