Deputy District Attorney Casey Ayer has seen the pattern too many times. In her four-plus years serving as a Nevada County prosecutor, Ayer has prosecuted probably hundreds of domestic violence cases as head of the office’s family violence unit. But in far more cases than she would like, Ayer said that she has had to drop charges against accused abusers — most often because of a lack of cooperation by the victim. “Victims’ stories change because their hearts change, and sometimes that ends up sinking the case entirely,” Ayer said. “Oftentimes, even when we believe we have a strong case to start with, it doesn’t end up a strong case.”