From the call released by the Sanford Police:
At 2:07, Zimmerman tells the dispatcher, “He’s running.”
At 2:09, you can hear a car door open and an alarm begins that is undoubtedly the “door open, keys in ignition” warning on Zimmerman’s truck.
At 2:13, you can clearly hear the car door slamming shut, and the alarm stops.
At 2:17, Zimmerman’s voice wobbles and he starts breathing heavily into the phone, indicating that he has started running.
At 2:22, without any prompting other than the aforementioned noises and breathing, the dispatcher asks “Are you following him?” to which Zimmerman responds, “Yeah.”
At 2:26, the dispatcher says, “Okay, we don’t need you to do that,” to which Zimmerman responds, “Okay.”
Zimmerman proceeds to give the dispatcher his name. Then he says, “He ran.”
Zimmerman can still be heard breathing into the phone until about 2:39, at which point the heavy breathing stops entirely, a mere 13 seconds after the dispatcher asked him to stop following. A very calm and collected Zimmerman then proceeds to give the dispatcher his own information, directions and a description of his location for another 1 minute and 33 seconds.
The difference between someone running while on the phone and not running can be heard quite clearly, and I encourage readers to listen for themselves.
There’s another reason to believe that Zimmerman stopped following Martin: After he gives the dispatcher his personal address, at 3:35, he says, “Oh crap, I don’t want to give that all out. I don’t know where this kid is,” meaning he is worried Martin might hear where he lives. If Zimmerman doesn’t even know where Martin is, would it even be possible for him to still be following Martin at this point? Would it even be possible for him to have continued following Martin after hanging up the phone — a full two minutes after he first got out of his car and a minute and a half after he fully stops breathing heavily — unless Martin came back and revealed himself?