Columbia University President Claire Shipman was booed during a graduation ceremony on Tuesday, with chants of "Free Mahmoud" heard drowning her out. Mahmoud Khalil, a Columbia University graduate was detained by US immigration officials in March over his role in pro-Palestinian protests on campus. He is a permanent legal US resident and has not been charged with a crime. Mr Khalil remains in detention in the US while official seek to deport him. President Donald Trump has called past pro-Palestinian protests antisemitic, but student activists deny this.