JOPLIN, Mo. (AP) — A Joplin woman believes her mother may be among six people whose bodies were found in two cars at the bottom of an Oklahoma lake.

Divers were conducting a training session this past week when they discovered the cars.

The Joplin Globe reports that Jo Irick became worried in the spring of 1969 when the letter she sent to her 58-year-old mother, Nora Duncan, came back unopened.

Also missing were the Canute, Oklahoma woman’s close friend, 42-year-old Cleburn Hammack, and another man, 69-year-old John Porter. Irick says some thought at the time that the trio may have gone fishing.

Irick says she has heard from the state medical examiner’s office about the possibility that her mother’s remains were in the lake. Positive identifications could take months or years.