Dave Taylor / Davey Herold Question

[John E.]

Hi Folks,

A few years back, Dave Taylor asked a simple question:

What is the source for Davey Herold accompanying Lewis Powell to Seward's home on April 14, 1865 ?

Forgive me if this has already been revealed but the first source I am aware of came from George L. Porter. Has this already been resolved?
Just for the record - I believe this was an assumption on his part.

John