IM Laurusas won his game with an illegal move!

Without knowing IM Laurusas won his game with an illegal move!

Black played his rook from a8 to a7 and back earlier in the game. Some moves later he castled qeenside. After the game he suddenly realises that castling queenside was illegal.
(10th RTU Open Round 6 , Riga)

Видео IM Laurusas won his game with an illegal move! канала itshenkjan