Egnoski was last seen in Delavan, Wisconsin sometime in 1966. Her disappearance was reported to police, but they didn't investigate it at that time. Egnoski's family hired private investigators who said she'd taken a bus to Chicago, Illinois, but there was no sign of her after that. She has never been heard from again.

In 1973, Egnoski's driver's license and Social Security card were found in the custodian's office of Wileman Elementary School in Delavan. Egnoski's father had been employed with the school as a custodian. In 2002, police investigating Egnoski's case dug at the house in the 1000 block of Center Street where she'd lived in 1966. Her family sold the home in 1971. Investigators found a crawl space under the house, but it was empty. No evidence was located during the search.

Egnoski's case remains unsolved and the circumstances of her disappearance are unclear.