WHITTIER, Calif. -- Eun Ha Lee says her 19-year-old son, Paul, could not speak and had the mind of a three-year-old.
He was picked up at his family's home Friday morning but never made it home that afternoon.
His mother called his teacher and found out that Lee never made it to school that day.
Police eventually found his body on the bus.
His mother believes Lee was left there all day in temperatures above 120 degrees with no water.
No arrests have been made but police are treating the death as suspicious.