Peter

Ah, I see. Your ETA didn't sufficiently clarify the issue in my head, perhaps due to the 'or some such'. So the question is whether the legal system knows that Bob committed some burglary on that day, and not either of whether he committed burglary at all (which it clearly does know due to his previous convictions) or whether he committed this specific burglary (which it clearly doesn't know).

I think my answer is still no, though. Suppose his alibi had been that he'd been out elsewhere committing murder. He might still have confessed to the burglary (on the basis that it carried a lighter sentence and would act as an alibi should he come under suspicion for the murder), and then it would clearly not be true that the legal system knew he had committed burglary on that day (because he didn't, and lied and said he did). No evidence relating to where Bob really was is involved in the legal system's justification for believing he committed burglary, so I think it's reasonable to say that the question of whether its belief constitutes knowledge ought not to depend on where he really was either.

This is one of those situations in which a belief is both justified (in that the legal system has good reason for thinking it), and true, but still not knowledge because the justification doesn't connect up with the truth – the justification is in error, but the erroneously derived fact turns out to be true anyway for a different reason. Like this incident.