Marks accompanied her mother to the San Joaquin County Mental Health Department in Stockton, California on October 18, 1988. Her mother was employed at the department. Marks then walked alone to the Department Of Motor Vehicles (DMV) on Parks Street to get an identification card. She is known to have arrived at the DMV, because her card was mailed to her several days later. Marks called her mother at work after leaving the DMV. She was unable to reach her and left a message on the answering machine. During the message she did not sound as if anything was wrong. She has never been heard from again.

Marks was supposed to meet a friend before she began work at 5:00 p.m., but did not keep the appointment. She did not take any personal belongings besides her purse when she went missing. She never retrieved her last paycheck from her place of employment, Rick's New York Style Pizza, where she was a waitress. Foul play is suspected in Marks's case. She had moved to California only a few months prior to her disappearance.