Evidence is starting to come out confirming Zimmerman’s story that he told the police. That he was attacked from behind when he was returning to his truck, knocked to the ground and than had his head smashed into the pavement by Martin.
IF, major if, his account of the events proves to be true than it looks like he was well in his rights to use his handgun.
Link to said article about the evidence: http://usnews.msnbc.msn.com/_news/2012/03/26/10868250-report-police-say-evidence-indicates-trayvon-martin-attacked-zimmerman