Link given is to CNN video of Zimmerman's brother, who says http://www.cnn.com/video/#/video/bestoftv/2012/03/30/piers-morgan-robert-zimmerman-george-zimmermans-gun.cnn that while Trayvon was busting Zimmerman's head on the concrete, Trayvon realized Zimmerman had a weapon, verbally issued a deadly threat towards Zimmerman's life, and followed that threat with an attempt to take control of Zimmerman's gun.