Thanks VF. I hear you on some pics giving you writer's block when you first see them and having to come back later when the creative juices return. Luckily, CW gives you plenty of time to come up with something before you are too late!
A genius move by Fincher and writer Andrew Kevin Walker is the way the violent acts are implied and not seen. We see the aftermath, just like the detectives do. At the end when John Doe explains to Mills in the desert what happened with Tracy: "It didn't work out." We're forced to imagine how that played out, and once again, only see the results of the criminal act. In fact, the only time we see a truly violent act in real time is at the very end.