When firefighters responded to a car burning off the side of Interstate 10 in Arizona, it looked like a routine highway fire. But hidden inside the vehicle was the body of 22-year-old Mercedes Vega, and investigators quickly realized this was one of the most horrifying cases they had ever encountered. As detectives dug into Mercedes’ final hours, they uncovered a trail of disturbing clues: blood in her apartment parking garage, surveillance footage capturing her last known moments alive, abandoned vehicles, and evidence suggesting she may have been targeted long before the night she disappeared…