Authorities quizzed Thursday an Egyptian who returned to Cairo a day earlier after completing a U.S. prison sentence for aiding his detained brother, who was a key planner of the 1993 bombing of World Trade Center, officials said. Mohammed Abouhalima, 41, was sentenced to eight years prison in late 1998 for helping his brother, Mahmoud, flee New York after the Feb. 26, 1993 attack that killed six people and wounded more than 1,000. Mahmoud Abouhalima was arrested in Egypt several weeks after the 1993 bombing and was eventually sentenced to 240 years in prison for his primary role as a key planner of the attack.It was not immediately clear how long Egyptian authorities would hold Mohammed Abouhalima. U.S. security personnel handed the Egyptian over to local authorities at Cairo's international airport, the officials said. There was initial confusion over the identity of the man returned to Egypt and it was unclear if he returned as a result of completing his U.S. prison term or for another reason. His brother was linked to a radical Egyptian cleric, Sheik Omar Abdel-Rahman, who Egyptian authorities blame for a wave of extremist violence in the mid-1990s.