In their senior year at Wayland High School, Genevieve Madelaine Flynn considered Nathaniel Fujita a friend: They hung out with the same tight group, ran track together, and he was dating her best friend, Lauren Astley.  

On Wednesday, Flynn’s voice shook as she identified Fujita in Middlesex Superior Court in ­Woburn;  she wept as she remembered the last day of Astley’s life.