Suleiman abu Ghaith is Osama bin Laden's son-in-law. A spokesman for al Qaeda in the aftermath of the 9/11 attacks, he threatened Americans with more attacks on airliners and high rise buildings. After disappearing for ten years, in February he was seized by US operatives in Jordan. On Friday he turned up in a courtroom in Manhattan, to plead not guilty to charges of conspiracy to kill Americans. Who is abu Ghaith? Where has he been for the last decade? What does he know about possible terrorist plots? Should he be tried in a US court in New York or transferred to Guantanamo for a military tribunal?