Well obviously he did it from the grave - everyone knows that.
I should have written Plumbers OF Watergate. Yes Hoover died a couple of months before. But both Liddy and Hunt said they were being stalked for more than a year, and they knew Hoover was behind it. Interestingly enough, it was really all for naught. There was nothing the democrats had that could have stopped Nixon, but his need to know forced the Plumbers to continue on when they already knew someone was setting them up.