How to stop an investigation dead.

Replace the prosecutor with a friend of the accused. Now why didn't Nixon, Reagan or Clinton think of that? From Firedoglake:

Instead of nominating local, qualified attorneys whose philosophy jibes with the
administration (as was the traditional practice), the nomination of U.S.
Attorneys has been subsumed into the Republican Party's political machine.
Apparently the title of U.S. Attorney is just too attractive a resumé-fattener
to dole out helter-skelter. And while you're fattening the resumés of possible
future stars of the party, it can't hurt to knock out a prosecutor who was
doing considerable damage to the party.

The administration has tried to say that the US Attorneys were let go for "performance issues." It turns out that was a lie. I am sure you were all surprised by this.