How many? Necessary if they plan to be alive to testify
Only enough to capture all the evidence, imo. Get people fairly high-ranking but you don’t want to go too high as the top dogs need to be held accountable.
Think Sammy “the Bull” Gravano.
Priestap seems to fit that description.
With each group (FBI, DOJ, Obama WH, Clinton Foundation, etc.) look for people that should be dirty, not the most senior, and are conspicuously silent, “like holes in the water.”
Could be that not all of them have been procured as of yet.