This is just what I vaguely remember, so don't hold me to it.
KGBeast was a KGB agent sent by Russia to assassinate the President. Batman got on the case to stop him. After Beast beat Batman in a fight once or twice, they take their final fight into the sewers. Batman managed to break Beast's arm, and Beast tries to get Bats to come into some room for a final showdown. Batman refuses, closes the steel door on the room, and boards it up. The picture above is the only thing Batman ever told the police on where he left him in panel, and since Beast didn't appear again until over a decade later in Face the Face (I think) where he was killed by the Tally Man to frame Two Face, many readers assumed Batman left KGBeast to die in that sealed room.