Political Red Herrrings
You wrote:
[...] because every legitimate and traditional path for the required investigation was blocked by Republicans.
As I see it, Bush's prevarications are quite obvious, but pointing fingers across the aisle has gotten us nowhere. As Thomas Pynchon put it in Gravity's Rainbow:
If they can get you asking the wrong questions, they don't have to worry about answers.
Let's not forget that it was Democratic Speaker of the House Nancy Pelosi who blocked moves to impeach Bush:
“I have said it before and I will say it again: Impeachment is off the table,”
as was reported in this NY Times article just after Democrats swept to power in '06.
Partisan squabbling between Democrats and Republicans only serves to distract attention from the real scoundrels, and that's just the way they finagle it.
S