Does anyone know...?

[RJNorton]

In her testimony, she heard one of the three men say the name "Jim".

Maybe, in the hushed tones, she mistook "John" for "Jim." (?)

I am disturbed by the fact that she apparently kept what she heard to herself until 1867. She supposedly overheard a conversation in which Abraham Lincoln, Mary Lincoln, and Tad Lincoln "could be got rid of," and she doesn't go to the police?

If what she heard were true, I wonder which one said that Mary and Tad could also be targeted. Booth liked kids, and he apparently once gave Tad Lincoln a rose backstage during a performance at Grover's Theatre (p.139 of Terry Alford's Fortune's Fool). IMO, Booth would not have said this. So that leaves Herold or Atzerodt. If I were a betting man, I think I'd bet on Herold.