[CanSpice]

According to Wikipedia, Harris's slot machine hack wasn't discovered. He turned to Keno, finding a flaw in the pseudorandom number generator, and when his accomplice went to cash in a high-value winning ticket in New Jersey, the casino got suspicious, alerted investigators, and everything came out after that.

[giarc]

Interesting. Sounds like a lot of these people get caught when they either get too greedy, or when they try to expand too much.