20/20 Season 49 Episode 16 Tracking Susana

On a hot summer night, 16-year-old Susana Morales was visiting her friend's house when she seemingly disappeared. A tracking app on Susana's phone showed her walking home, then suddenly going the opposite direction in a car. Minutes later, her phone registered a crash alert, yet there were no signs of an accident and no signs of Susana at the location. After reporting her missing, Susana's family took matters into their own hands, retracing her steps and uncovering surveillance video just minutes before she vanished. In a heart-pounding investigation, explosive video tracks detectives — in real time — as they hunt for clues in Susana's disappearance. Six months later, a critical breakthrough led authorities to Susana and to a piece of evidence that broke the case wide open. ABC News correspondent John Quiñones speaks to Susana's mother and reports on the shocking discovery that uncovered someone no one had anticipated.