In a "friendly" blitz game I got into an argument with my opponent in the following scenario:
My opponent's knight was pinned to his king. He did not notice and touched his knight to move it. I became excited and before he had a chance to press his clock, I took his king.
The question is: by official rules does my opponent lose the instant he touches the knight? (Making any action taken after this instant irrelevant?) Or does he need to "complete" the move by pressing the clock?