I did a little research on the guy earlier when I saw this.....he’s a liberal Hillary/Obama lover and likely one of the underlings knowing they ‘served’ the wrong side so they’re jumping ship......expect more.
Additional to that thought......he may have been already squeezed dry and allowed to take cover out of harm’s way
That’s my guess
You needed to research that? The fact that his resignation letter made it to the New York Times pretty much tells you he was politically corrupt partisan hack first and an FBI agent second. Another leftist another statist.