More than a year and a half has passed since Jennifer Gelvin, singer for the Fabulous Boogienauts, and neighbor Katherine Pivoda were stabbed to death at Pivoda’s home by Matthew Madden, Pivoda’s estranged ex-husband. On June 30, 38-year-old Madden was finally sentenced in Denver District Court for killing Gelvin and Pivoda; he’d pleaded guilty to two counts of second-degree murder in April…