CHICAGO—A man charged with killing a Chicago police officer admitted to investigators that he pulled his handgun out of his waistband during a traffic stop and opened fire, a prosecutor told a judge Tuesday. At a bond hearing for Monty Morgan, Cook County Assistant State’s Attorney James Murphy provided the most details yet disclosed about the weekend traffic stop in which Officer Ella French was killed and another officer was critically injured. A third officer fired back at Morgan, who did not attend Tuesday’s hearing because he remains hospitalized. At the conclusion of the hearing, Cook County Judge Arthur Willis ordered Morgan—previously identified as Emonte Morgan—held without bond on charges of first-degree murder of a peace officer, attempted murder of two other officers, unlawful use of a weapon, and aggravated unlawful use of a weapon. “They didn’t have their weapons drawn, they weren’t firing on him, and callously (Morgan) shoots …