Tina Duffell was 37 and working part-time at a convenience store in Quapaw, Oklahoma, when she vanished during her shift on October 17, 1974. Her purse and keys were left on the counter beside an unfinished soft drink; about $250 and some beer were missing from the store. Her body was found the next day in a mining pond northwest of Quapaw, weighted with timber. An autopsy showed she had been stabbed in the back and her throat cut.

Before her death Tina had reportedly left a letter with the local postmaster to be opened only if something happened to her, then retrieved it shortly afterward; the contents are not known. Investigators looked into rumors that she might have uncovered information about local drug dealing, and a woman later told Tina’s husband she had seen the letter and feared for her life, but that witness later recanted, saying the only letter she knew about was one Tina wrote to the school board.

The case went cold and was officially reopened in 2003 at the family’s request; witnesses were re-interviewed and the autopsy re-examined, but no arrests were made. Karl Lee Myers, a convicted murderer and rapist who lived in the area at the time of Tina’s death, was considered a person of interest but was never charged. Who in the Quapaw community that autumn of 1974 might still have information about Tina’s last hours or the mysterious letter?