We make celebrities out of serial killers. They're glamorized and romanticized. People forget about the gruesome details of their crimes.
In some cases, this may actually make the difference. It has an impact on those people who aren't rigidly in favor of the death penalty, but who could still change their minds.
Gossip, then, is content, a message about people; rumor is a process. It takes a bit of gossip and reshapes it, modifies it in some way, and passes it along from individual to individual in different ways.
These things take a while to sink in before people decide they're not going to take it anymore. I don't think we're there yet.
These are people who are alienated and don't really identify with their fellow residents in any positive way. They feel the tragedy is an opportunity for them.