Mason Michael Joachim, 26, was arrested for allegedly crashing into 33-year-old Nancy Arzate on Interstate 15 in Temecula, resulting in her death. The incident occurred when Arzate lost control of her vehicle and became stranded on the freeway late Saturday night. Joachim, driving at approximately 70 mph, struck her vehicle while she was outside, then fled the scene on foot. Despite attempts by bystanders to provide aid, Arzate was pronounced dead shortly after. Prosecutors have not filed charges against Joachim due to undisclosed evidentiary issues, and the case has been returned to the California Highway Patrol for further investigation. Joachim remains in custody with a bail set at $1 million, facing potential charges of second-degree murder and DUI.