On January 15, 2017, 26-year-old Ryne Zahner, a math teacher at Mesa High School, was shot and killed in the backyard of his Tempe, Arizona, home while talking with a friend by a fire pit. An intruder identified as a former friend and roommate, Caleb Bartels, opened fire with an automatic rifle. Zahner was struck by multiple bullets and died at the scene. The friend tried to wrestle the rifle away, then fled to call 911; that eyewitness account helped investigators quickly name Bartels as the primary suspect.

Authorities believed Bartels had fled the state and considered him armed and dangerous. He was located and arrested near the California-Nevada border on January 22, 2017, after an off-duty California Highway Patrol officer recognized him. Receipts for the rifle and matching ammunition were found in Bartels’ vehicle and matched shell casings from the scene. The motive for the killing remained a central issue during the investigation and trial.

Did anyone who knew Ryne or Bartels recognize the pattern of tension between them or have information that wasn’t shared during the investigation?