This is part 1 of 2, of a video replacing an earlier clip I had uploaded to YouTube, but deleted as I determined it contained an error.
The first two 911 calls responding to the Trayvon Martin/George Zimmerman altercation can be definitively matched to the start times recorded in the Sanford 911 logs. Both were placed before the gunshot occurs. The other 4 calls (see part 2) were placed after the shot. The probability that I have matched these calls to their correct start times is fairly high, given the clues in the content, but nowhere near "scientific certainty."
Key points: 1. The first call definitively places the time of the gunshot at 7:16:58. 2. The first call establishes that there was at least 45 seconds of screaming before the shot. 3. Many media accounts indicate that police arrived at the site of the shooting at 7:17. Although the Sanford police report states the police arrived at 7:17, this references the fact that the first squad car to arrive, driven by Officer Timothy Smith, entered the complex at 7:17:XX. The second 911 call clearly places Officer Smith on the wrong side of a large building from the actual scene of the shooting as late as 7:18:20.
ANALYSIS Leaks from the SPD, and statements from the Zimmeman family have presented George Zimmerman's account of events as this: Zimmerman was attacked by Trayvon Martin and knocked to the ground, at which point Martin assumed a superior position over him, holding him to the ground while repeatedly pummeling him with his fists and banging his head against the sidewalk.
This account is inconsistent with the evidence on two points. 1. It is difficult to imagine how Martin could have held a superior position and beaten Zimmerman as described for over 45 seconds without Zimmerman receiving serious injuries. 2. The witness in the fourth call describes the two men as "wrestling" which would be an unlikely word to describe a one-sided beat-down.