The gun used to kill unarmed black teenager Trayvon Martin in a 2012 case that triggered protests across the United States was put up for auction Thursday. Former neighborhood watchman George Zimmerman, who shot dead the 17-year-old, listed the weapon on the United Gun Group's website -- hours after it was removed from a prevous site which said it wanted nothing to do with the sale. "Mr Zimmerman never contacted anyone at GunBroker.com prior to or after the listing was created and no one at GunBroker.com has any relationship with Zimmerman," the website said in a statement.
