What Was The Role of David Herold

[wsanto]

He doesn't sound like the kind of soldier you would hand-pick for this kind of mission. If I was Mosby or another Confederate Officer looking for the man to help in the mission to assassinate Lincoln and Seward, I wouldn't pick the guy in my unit that is helping to save the lives of Union soldiers and not cleaning his gun. I would pick a killer, an assassin.

Is there any indication as to how he got messed up in this business in the first place?