A new lawsuit raises the possibility of Tehran's complicity in al Qaeda's infamous attacks. Philip Shenon reports fresh details on who will testify—and the mysteries they could unlock. With the 10th anniversary of the 9/11 attacks looming, a federal lawsuit in Manhattan offers the possibility of resolving a central mystery about the attacks: Was Iran involved? Former investigators on the 9/11 Commission, which uncovered tantalizing but inconclusive evidence of Tehran's ties to the plot, tell The Daily Beast they welcome the lawsuit, because they believe the U.S. government has done little to follow up on the commission's evidence of Iranian...