Or HaChaim on Leviticus 4:23/אור החיים על ויקרא ד׳:כ״ג

1 או הודע אליו חטאתו, or he has become aware of his inadvertent sin, etc. The Torah here writes "or" seeing in the previous verse it had written ואשם, that he was definite about having sinned. Torat Kohanim concludes that the ruler has to bring an אשם תלוי, a conditional sin-offering, if he is in doubt about having committed the sin in question. Our verse may discuss a situation where after having first offered an אשם תלוי while he was in doubt, the ruler now has to offer a definitive sin-offering as he is now certain that he committed the sin he had been in doubt about.