Ann was last seen in Newhall, California on March 22, 1991. She dropped off her three children at the residence of her husband, John Racz, near Valencia, California during the day. She planned to purchase hambugers at a nearby McDonald's afterwards, but she never returned to pick up her children and has not been heard from again.

Ann had separated from her husband four days before and filed for divorce. She was already seeing another man at the time. Racz moved into a condominium with their children. Ann's Plymouth station wagon was discovered abandoned near the airport in Van Nuys, California on April 26, 1991, more than one month after her disappearance. There was no sign of her at the scene.

John claimed that Ann departed on an extended trip and he gave her $25,000 to spend. He said he spoke to her on the telephone after she left. Authorities never believed that Ann left her home voluntarily and suspected that she was the victim of foul play. After Ann's disappearance, a cold pizza was found sitting on the kitchen table in her condominium. Investigators considered this to be odd, as Ann was considered a meticulous housekeeper who would not have normally left food out. She had gone on vacations before, and whenever she did so she would pre-address mailing labels so she could send postcards to her loved ones. At the time of her disappearance, Ann was a well-known and popular community volunteer who worked at her children's school and at Newhall Presbyterian Church. None of her friends or family have heard from her since March 1991.

An extensive search of a ten square-mile area of Pico Canyon in mid-1991 produced no evidence related to Ann's case. The location was selected due to its proximity to her last known location. Authorities also utilized the services of psychics several years after Ann disappeared. The psychics' visions directed the search towards the Spring Canyon area of California, but excavations were unsuccessful.

In October 2006, John was charged with murdering Ann. The grand jury issued the indictment after hearing testimony from 19 witnesses, including the couple's children, who are now adults. Investigators dug up his backyard in September 2006, expecting to find Ann's body, but the search revealed no evidence. Nevertheless, they felt the case was strong enough to go to trial, since Ann was such a methodical woman who would be unlikely to vanish on her own. In addition, she had told friends she was afraid of John and thought he might kill her and hide her body so no one could find it.

John was convicted of first-degree murder in August 2007. He was sentenced to 25 years to life in state prison. At sentencing, John maintained his innocence in his wife's disappearance and stated she left him of her own accord. Ann's remains have never been located.

Some agencies may list April 24, 1991 as the date of Ann's disappearance.