The murders of two prosecutors in Kaufman County, Texas, apparently has prompted a federal prosecutor to withdraw from a major racketeering case in Houston, the latest sign that attacks on lawmen are having a chilling effect on the judicial system. Assistant U.S. Attorney Jay Hileman sent defense attorneys an email Tuesday saying he was withdrawing from the case against the Aryan Brotherhood of Texas due to safety concerns. “I understand why someone would want to step back, and it makes sense to me, especially people who have families,” defense attorney Richard Ely, who is representing one of the defendants in...