Amnesty International Director Colm O'Gorman has said there are hopes that the case of Ibrahim Halawa may be "moving slowly to some sort of conclusion".
Mr Halawa, who is 21 and from Firhouse in Dublin, was arrested in Cairo in August 2013 during protests against the ousting of then president Mohammad Mursi.
Speaking on RTÉ's Morning Ireland, Mr O'Gorman said seven police officers were yesterday cross-examined about what happened in the lead-up to Mr Halawa and the other defendants being arrested.
None of the police officers were able to identify any of the defendants, he said.
Mr O'Gorman added: "All of the state witnesses who have been presented before the court have confirmed everything that we said. That there isn't any evidence in the prosecution's case or files to link Ibrahim to any of the serious charges that have been laid against him.
"If we are to see anything positive in this, and it is difficult to do that, there is nothing to link him with the charges he is facing."
The case has now been adjourned for two weeks.
Mr O'Gorman said Egypt is gravely violating Mr Halawa's human rights.
He added: "We are very concerned about his physical and mental health. He needs to be immediately released."
"He has on occasion stopped taking food and water and is obviously desperate about the situation he is in. He can see no end in sight to this."