I've never understood why dispatchers always tell people to not follow someone. If you are reporting a suspicious person then wouldn't you want someone to keep a visual tab on them until the cops get there? If Zimmerman had made it back to his vehicle and drove off then Martin could have disappeared into the night and who knows what would have happened at that point. Cops aren't magicians, they can't just majically know who the suspect is. Wouldn't you be ticked off if you found out that some potential killer or rapist was on the prowl and someone had a visual on him, but the 911 operator told them to "go home"? I feel Zimmerman was justified in his actions and should be found not guilty.
My understanding is that dispatchers never give direct orders, but speak in more general terms, because then they may be held responsible.
If a dispatcher orders someone not to follow a suspect, and the SHTF, dispatcher will be blamed, and vice versa. Therefore "We don't need you to do that" and "try to keep an eye on the suspicious person, sir".
Wiggle room.