According to ChessBase, a German company that sells chess software including the classic Fritz chess engine, some of their founding members were the first ones to try using computers to cheat at chess, “for science” as they say.
Pfleger was still winning the majority of his games including the one played strictly against the computer’s moves. While this was ostensibly an experiment, it might be the earliest example of an attempt to use a computer to “cheat” against a grandmaster. The fact that AI has progressed so much since Deep Blue’s win against Garry Kasparov in 1997 makes this early “Turing test” feel all the more like a canary in the coal mine for the wider chess world.