Cyncor-McMillan was last seen at Davenport Beach in Santa Cruz County, California on March 9, 2009. He was camping with five friends and he and one of them decided to go for a swim at 4:00 a.m. The two of them made it to a rocky outcropping offshore, then started the swim back. Cyncor-McMillan's friend arrived onshore safely, but Cyncor-McMillan disappeared and has never been heard from again. He is a strong swimmer and had been as a junior lifeguard for years with the Capitola Junior Lifeguards. The water temperature was about 50 degrees that night, with ocean swells of up to 12 feet.

Cyncor-McMillan is presumed to have drowned, but his body has never been recovered. His father and friends set up an annual memorial scholarship for him at Los Gatos High School, where he was a senior and a member of the football team.