Mattie Lou Zabel, 45, a teacher’s aide from Cedar Falls, Iowa, was last seen by family on March 21, 1978. That evening she left a frozen chicken thawing in the kitchen sink and did not take clothing or personal items. The following day her son found her car at Black Hawk Park with her purse locked inside; that park was a place she often walked.

Authorities conducted an extensive search with dogs, divers and a National Guard helicopter but found no trace of her. Police considered that she might have accidentally fallen into the Cedar River or died by suicide; she had been treated for depression though her psychiatrist reported improvement before she disappeared. Her credit cards were never used and she lacked means to support a voluntary disappearance.

Mattie was declared legally dead in 1985, but the case remains unsolved. If anyone knew Mattie, saw her around Black Hawk Park in March 1978, or has information about her whereabouts, please contact the Cedar Falls Police Department.