Peggy Joyce Jones Mandeville was 39 when she disappeared from the Camarillo/Oxnard, California area on or around September 1, 1978. She was described as 5 feet 2 inches tall, about 100 pounds, with brown hair and green eyes. She may also have used her maiden name, Peggy Joyce Jones.

In 1978 Mandeville had been admitted to Camarillo State Hospital for treatment of chronic depression. Sometime in September she left the hospital and called both her mother and her husband from a pay phone; those calls were the last known contacts. Camarillo and Oxnard police investigated, and the Cape Girardeau Police Department in Missouri — where her mother lived — also filed a report after her mother reported her missing. Her mother never moved or changed her phone number and died in 1997; the ex-husband later filed for abandonment before pursuing divorce and died in 2019.

There has been no public resolution of her disappearance. If anyone knew Peggy, where she lived, worked, or might have gone after leaving the hospital in 1978, please share what you know with investigators.