Tom,

The questions that trouble you ("Before the age of 25, did you ever steal anything?" and "Did you ever steal anything from a previous employer?") are both "probable-lie control questions." You were secretly expected to have considerable doubt about the truthfulness of your answers to these questions, or even to blatantly lie in response to them.

The "test" is scored by comparing reactions to these probable-lie control questions to your reactions to corresponding relevant questions (for example, "Are you responsible for the non-delivery of that missing piece of mail?")

If you react more strongly to the "control" questions, you are deemed to be truthful regarding the relevant questions. If you react more strongly to the relevant questions, you are deemed to have answered them deceptively.

Thus, your having doubts about your answers to the two questions you mentioned would have tended to "help" you to pass the "test." The problem is that polygraph "testing" has no scientific basis to begin with. Fear of the consequences of not being believed when truthfully answering the relevant questions can easily result in a false positive outcome.

For more on polygraphs, see our e-book, The Lie Behind the Lie Detector, especially Chapters 1 & 3.

Since you are evidently now suspected of a felony crime, I think it would be wise not to speak further with investigators without a union steward and/or lawyer present.