Yinzhou Zheng, a 46-year-old graduate student at the University of Missouri in Columbia, was last seen on September 17, 2000. He planned to visit his daughter in Iowa City for the week and told his son he would return on September 23, but he never reached Iowa City and did not make contact. His vehicle remained at the family home in Columbia, and both his and his wife’s passports were found there, making an international trip unlikely.

A week after Yinzhou’s disappearance, on September 23, 2000, his wife Xiang Sun also vanished. She had gone to work, come home and gone to bed the previous evening; by morning she was gone. The two disappearances, occurring within days of each other and leaving few tangible clues, shifted the case from a single missing person to a missing couple investigation handled by the University of Missouri Police Department.

Those who knew the Zheng family or saw anything around mid- to late-September 2000 in Columbia or Iowa City are asked to come forward with information.