An entry in Fortnightly Topic Challenge #40: Retrograde Analysis!
Of course, the Black Kingdom must have done this, but we have no idea how. The remaining White soldiers are calling foul play, and I'm certainly one of them. In fact, we're going to take it to one of the most prestigious courts in all of Chesslandia to make sure their checkmate was fair. We have four eyewitnesses: myself, the bishop on g1, the pawn on f2, and the pawn on e2. We each have our one piece of evidence, but... I think one of us is a spy who will lie about the evidence to make sure Black gets off scot-free!
Here are our statements. I'm obviously not the spy, so my statement is truthful.
There was not a pawn on g2 on our turn 2 turns ago, but there was on our turn 3 turns ago, and I know for a fact it wasn't captured.
The knight on h1 is not a promoted piece.
The bishop on f1 is a promoted piece.
There was a piece on e1 on our last turn.
So, how did Black check our King? What were the last 3 moves? Who is the spy? And, most importantly, was Black cheating?
Please help. Our kingdom needs you!