The utterance of such a false thing, outside, maybe, a literal torture chamber, is depraved.

That may be so!

This is quite different from being a literally perfect indicator of guilt. I'd feel overconfident saying there was a 95% chance I could keep my story straight if accused of murder, never mind in another country and another language.

Part of this may be calibration. 2.00 obviously isn't even a probability, but even if I assume your 1.00 figure is simply rounded to two decimal places, it would require that less than one person in one hundred who changes their story is actually innocent. I doubt that is the case.