Dublin-based Front Line Defenders says on Tuesday that Ibrahim Metwally Hegazy was arrested at Cairo International Airport two days ago while traveling to Geneva for a UN meeting on enforced disappearances.
He and his son provided legal services to the family of Giulio Regeni, a researcher who disappeared on January 25, 2016 in Cairo and was later found tortured to death.
Hegazy's whereabouts are unknown.
Italian prosecutors have complained that Egypt is not cooperating in the unsolved case. Italy recalled its ambassador in protest but recently announced a new one would return, citing some improvement.