The third sentence always ruins it

I was just reviewing a fraud case where the suspect kept saying, 'I didn’t do it, but I can see why you’d think that,' and then—boom—the third sentence. That’s when they either confess or start sweating. It’s like the brain gives up halfway through lying. I’ve seen it in spreadsheets too. The one line that doesn’t add up? Usually the third one. Not the first. Not the last. Always the third.