Twenty-five years ago, Selena Quintanilla-Perez was already a legend in the Tejano music world and on the verge of superstardom. But on March 31, 1995, Selena’s close friend Yolanda Saldívar pulled a gun from her purse and fired a single bullet. Selena was pronounced dead a short time later. Selena’s murder left her family, friends and fans around the world stunned, heartbroken and speechless. In the days, months and years that followed, one question would linger: "why?" Why would someone who claimed to be the singer’s best friend, someone so close to her, choose to end her life? What...