Prison historians are hoping a public awareness campaign will help them track down the only keys to the gas chamber Missouri State Penitentiary.
The keys went missing in 2005 during a private tour of the newly closed prison, and without them nobody has been able to get into the gas chamber's two holding cells.
The Jefferson City News Tribune reports the original locks eventually might have to be replaced or welded so they no longer latch.
The keys were individually cut by the prison's locksmith in the 1930s and are the only witnesses to all 39 state executions at the institution between 1965 and 1989.
Former deputy warden and current MSP historian mark Schreiber says returning the missing keys would show respect for the prison's history.