McHan was last seen in Stockton, California on June 7, 1981. She was on her way home from visiting friends in Sacramento, California when she stopped at a gas station to get fuel for her car, a canary-yellow 1974 Toyota with a black vinyl top. The attendant at the gas station noticed two men harassing McHan, and asked if she needed help. She told the attendant she would be fine. She has never been heard from again and her car has never been located.

McHan was a student at San Joaquin Delta College at the time of her disappearance. She is missing under suspicious circumstances and her case remains unsolved.