It required making an ordinary observation: "Hey, these things don't look like they were typed in 1972." It just required being part of the real world.
Exactly what I wrote when I read that it was being argued that obviously it was some young kid who made the forgeries. No, more likely it was some insulated weathly career guy (military? entertainment?) who has always had subordinates doing all the 'details' stuff. Then when he needs to produce these forgeries he doesn't dare ask anyone, he takes to the keyboard himself.
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I think you have solved the mystery of who made the documents! I don't know about Burkett's financial status , but he retired from the [Army] National Guard as a Lt Col. so he was used to dictating docs, not typing them.
If he had subcontracted the task, so to speak, a professional forger would have done a less sloppy job.
My vote is still on Robin Rather until proven otherwise as the forger.
But still, I guess that we could consider that Mapes herself could be "Lucy Ramirez".