[The KG9 Kid]

Brief overview of answers here in a better thread covering this particular issue:

Deathbed Confession of Howard Hunt Fingers LBJ in JFK Murder

... And Freeplancer, there is no letter 'o' in the word 'genius'.

[Rockpile]

From the security angle one may suppose that the Secret Service keeps track of former Presidents and Vice-Presidents even if not actually guarding them.

For example, where would they have looked for Richard Nixon on November 22, 1963?

[freeplancer]

It was called self-depricating spelling nutznumb.