Chau was last seen in Portland, Maine on December 24, 2005. He was visiting his family for the Christmas holidays at the time. He was last seen on the couch at his family's residence shortly after 1:00 a.m. on Christmas Eve. Later that morning, his loved ones discovered he was missing. He left behind his wallet, car and car keys.

Chau had been an honors student at Portland High School, and after graduating he enrolled in the University of Maine at Orono on a partial scholarship. He majored in business. He had not registered for spring semester classes, however. He had financial problems due to internet gambling, and his family asked him to come home to be closer to them. Chau's loved ones stated he did not often discuss his personal problems with them, but it is uncharacteristic of him to leave without warning; they fear for his safety.