STOCKTON — An attorney representing the family of slain hostage Misty Holt-Singh has scheduled a news conference for 11 a.m. Tuesday at the University Plaza Waterfront Hotel in Stockton.Attorney Greg Bentley said Friday he will hold the news conference to discuss “developments and ongoing news” regarding the tragic death of Holt-Singh, who was killed July 16, 2014, in a gun battle between police and heavily armed bank robbers.