Getting to the bottom of what happened has proved virtually impossible - neither Manning nor several classmates who were with him that day have made statements to Internal Affairs investigators. A handful of neighborhood eyewitnesses have also remained silent.
"Nothing gets resolved if you don't talk," Ramsey said. "I've been here six years, and I think I've demonstrated that I will take action against a police officer who acts inappropriately . . . but I can't do anything if I don't have people come forward and speak."
Manning's lawyer, Lewis Small, previously said he wouldn't allow the teen to make a statement unless the crimes he was charged with on that frigid winter day - recklessly endangering another person, resisting arrest and simple assault - were withdrawn.
Williams said his office would use "every means that we have at our legal discretion" to get information about the incident. He did not rule out convening a grand jury.
Police surveillance footage has shown that Manning struggled with two patrol cops who stopped him after he was spotted running down Girard Avenue. The teen, who doesn't have a record, was on his way to his high school basketball game.
Williams said anyone with information can contact his office at 215-686-8000, or via email at email@example.com.
"At this point, we have no basis to believe that a police officer did anything wrong," he said. "If we find otherwise, we'll deal with it at the appropriate time."
On Twitter: @dgambacorta