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I am sorry to hear about this situation. Technically, this would be considered theft even if the person was caught and paid for it. Or rather, it may be considered attempted theft - still a criminal action.
So yes, technically he can still call the police and the police may charge someone in your situation with a low-level crime (I am assuming whatever the item was, it was not too costly). However, if the boss allowed you to pay for it and showed no intention of calling the authorities, it is very unlikely that they would do so now.
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