If the money was spent, how come none of it ever turned up in circulation?
Is there a scanner in every business where money gets spent? Was there in 1971? You can get the picture I think -- if in a reasonable timeframe after the hijacking and ransom someone opened a large, new account in a US bank, or made a large deposit in an existing acc't, perhaps someone would have started checking the serial numbers. A year or two later, not so much. Also, if the money were spent on everday needs and otherwise kept in the mattress as it were, it would very easily vanish into circulation, which is probably what did happen. This new claim notes that the suspect bought a house -- on land contract with only $600 down -- and a car -- in cash (perhaps from private party?), and used the rest of the money over subsequent years for other immediate needs of that kind.