they still voted to not hold a proper trial in the Senate. They did so knowing his defense was rooted in and making wide use of a Russian intelligence created conspiracy theory to shift the blame off of both Russia and the President, which was why the President had tried to squeeze Ukraines president for dirt on the Bidens in order to both validate the conspiracy theory and use it to damage VP Bidens campaign, and they allowed that defense to be presented without so much as a peep of objection. And then, knowing all of this, they voted to acquit him.
I don't think the relationship between trump's collusion with Russia during the 2016 election and later attempts to get Ukraine to provide dirt on the Bidens is pointed out often enough. It's obvious in context, but Democrats kept the impeachment hearings so laser focused that it was allowed to fade to the background. (For some of us, anyway.) It needs to be brought back to the forefront. The subject of the impeachment hearings was definitely related to this, the reasons why are obvious, and there is no way any member of the Intelligence Committee would be unaware of these facts.
They knew, and and refused to hold trump accountable, even for his Ukraine crimes -- likely because they were aware that once the Ukraine portion of the plot was completely out of the bag, the rest would naturally follow. Collusion indeed.