Mr. Watts said one of the boys delivered a single blow to the back of his head during the incident Saturday, knocking the victim to the ground. At one point, the victim recalled being lifted from the ground so one of the boys could “drop-kick” him in the chest. One boy, he said, put his foot on the back of the victim’s neck, with another shouting, “Kill him.” While Mr. Watts was down the boys kicked him, over and over, shouting, “[Get] that white [man]. This is for Trayvon … Trayvon lives, white [man]. Kill that white [man],” according to...