The criminals were later caught. Unfortunately I can't seem to remember any particulars. I've been asleep a few times since then. The problem on Wall Street was not too much automation but rather too little. The investment strategy which most obviously failed was portfolio insurance.
Portfolio insurance assumes quick trades.
The weak point was not the NYSE computers but rather the interface between them and the human traders. Futures contracts trading speed was limited by the speed of printers and human traders on foot in the NYSE floor. Liquidity seemed to vanish. Here are some responses to a few of today's postings. It seems the main problem is blindly relying on expert systems, because of lack of time and expertise.