Two more cases from the ATF's troubled gun-buying sting in Milwaukee have been dismissed, this time because the prosecutor says she can't use the operation's lead agent as a witness.Milwaukee County Assistant District Attorney Karen Loebel said in court Fridaythat she could not call U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives Special Agent Jacqueline Sutton to testify — the latest setback for an operation riddled with problems exposed bya Journal Sentinel investigation.Loebel, who has dropped eight of the 18 cases she charged from the 2012 sting, said she was not allowed to disclose why Sutton could not take the...