Imagine that each vote bought is a state felony and let's say we are dealing with a modest 2000 votes bought. Each vote is actually multiple felonies, not only the vote purchase but also at least one count of conspiracy per vote. The Rev. Mr. Fielder comes forward voluntarily and gets immunity from prosecution. That works to prohibit his prosecution at the federal level as well, I believe. It is reasonable to give him immunity because he can testify so as to convict EVERYBODY else.
Soon we find out whether the Mississippi chain gang has an Alzheimer's wing to accommodate former Senator Cockroach, whether special diets dependent on pork are available to Haley Boss Hogg Barbour.
This is a verrrrry nice development.