Nope. De-Saaad Possessed Mary Marvel killed (gruesomely) one of the Atomic Knights in Final Crisis #3 while attacking Wonder Woman. Up to that point even Mike Carlin (editor of Countdown) was making the point that "Black Mary", evil as she was, hadn't killed anyone yet in Countdown. Morrison had other ideas. Of course, Mary wasn't in control of herself but just the idea of making sweet girl-next-door Mary Marvel (of all characters DC/Morrison could have chosen) into a killer is vomit-inducing. Part of the reason I try to forget either Countdown or Final Crisis exist.
And of course the next time we see Mary I'm sure she'll be in therapy for all this. I know I would be.