Well that's the point of an impeachment proceeding. It's purpose is to provide a court wherein facts may be determined as to possible presidential malfeasance.
As for former KGB director Putin not knowing that someone under him "did the deed," or generally not knowing about Russian ops against the U.S., doesn't this seem pretty improbable? If it doesn't to you, I've got this great deal on a timeshare in Okeefenokee swamp to sell you! Amazing views!