"... witnesses were not permitted to participate or guide us to any solid conclusions..."
That's all you need to know.
The sonofabitch is guilty. He tried to bribe a foreigner with my tax dollars into helping him fix an election, putting my country's security at risk. And then when he was caught he did everything he could to try and cover it up.
And anyone who can't see that, or sees it but refuses to admit it, or collaborates in helping him get away with it, is just as guilty as he is.