Not only "not charged", but Zimmerman was not even questioned at the police station...AND then the PD allowed Zimmerman to leave the scene of the crime WITH his gun. The Sanford PD drug tested the victim, but no tests were applied to the shooter...the Sanford PD didn't use the victim's cell phone to determine who he was and listed him as "John Doe" for hours before his parents learned what happened to him.
As I was saying to Peg, arresting just means physically taking someone into custody, for a minute or an hour or a day. It's what police officers do.
Charging is the filing of court papers by the prosecutor who reviews the police info and decides if it's sufficient. If it's not sufficient, the person arrested is let go.
It can't happen simultaneously and it doesn't have to happen consecutively, which is what I think is occurring in this situation.
The police are investigating what happened, Zimmerman may still be charged.