I'm a CCW holder here in Illinois, and I assume Chapman was referring to the law here in Illinois, and what we CCW holders resposibilities are prior to shooting.
Going through the required CCW training here in IL, one is specifically instructed that if a perpetrator is in the act of FLEEING once confronted by an armed CCW holder, the CCW holder *must* let the perpetrator go.
For example, if someone breaks into my house in the middle of the night and I paint them with my laser and they turn to flee my house, I have to let them go. Shooting anyone in the act of removing themselves from the scene is not considered a "good shoot" here in Illinois.
Don't anyone bitch at me about that --- that's just what the law says. I personally don't agree with it, but I have to abide by it.
Here's an article from Massad Ayoob I just saw about the incident in question. Apparently the investigators took the citizen's side.