A question no one is asking: "What did he know and when did he know it?" 2-minutes-19-seconds

Why is no one asking, "What did he know and when did he know it?"

“There’s a reason no one has said, 'What did the President know and when did he know it?’ From  the  evidence you have  presented .... we know one thing, and one thing is clear: As it related to this scheme, the President of the United States, Donald J. Trump, knew everything.”  —  Rep.   Eric Swalwell, December 9, 2019