I believe its entirely possible that someone who has access to long lost records which were filed away in some storage room many years ago has decided to use this right now.
And that is the most glaring problem most people have with such events out of the past, that records were written or typed, copies were made, copies of copies were made and filed, filed in storage rooms, filed on microfiche.
There was no internet, no ISP, not electronic record keeping.
And then you have people who for some reason personally collect old records and files.
Another bogus report dropped onto the conspiracy theories like the bogus UFO sighting put out by the government to have the general public discount all the reports as unreliable.
Remember, too, that everything was done in triplicate. His mop up guys might have scrubbed a lot of information but there's no way they got to everything he's done and everywhere he's been over the last 50 years.