Leviticus 5:17

If a man sin, and do against any one of all the commandments of the Lord that which is not right to do, though he knew it not, he hath sinned, and shall bear his guilt;

if someone should sin by violating one of the prohibitions, but did not know that what he did was forbidden, he must bring a ram. According to the majority opinion, this is the adjustable guilt-offering; and it applies when someone does not know whether or not he did the forbidden act. The sin-offering applies when he originally did not know that something was forbidden, and found out after his sin. Thus the sin-offering applies as long as he did not know that something was prohibited, until the point when he knew. The guilt-offering applies: 1) when he originally knew that something was forbidden, and then forgot, and afterward remembered again; 2) in the case of the adjustable guilt-offering.

ולא ידע ואשם; the Torah discusses an אשם תלוי an offering pending clarification of the sin. This is why the Torah adds the rider על שגגתו אשר שגג והוא לא ידע, seeing that every שוגג, inadvertently committed sin, contains an element of being unaware of it, why would the Torah have to add the words “and he did not know?” [Had he known, the sin would have been deliberate and no sacrifice would exonerate him. Ed.] The error consisted of mistakenly eating something not kasher instead of picking up the similar looking kasher item next to it. At the time the person thought that both were kasher so that there was nod doubt in his mind. By the time he found out, the other piece had disappeared. If for some reason he becomes aware later that he had indeed eaten the forbidden piece of meat he will have to bring an additional sin-offering. The effect of the asham taluy protected him only until clarification of the true state of affairs.

ואשם ונשא עונו, our sages have a tradition that the Torah here speaks of an asham taluy, a guilt offering offered while the exact nature of the guilt is unclear. The person offering it is not even sure that he is guilty of an offence. Considering this state of affairs the Torah writes ונשא עוונו, he carries (the burden) of his guilt. The guilt is not spelled out precisely as it is not yet known. He may not actually have committed a sin, but this does not mean that he is free from guilt as had he been careful he would never have been in the predicament of not knowing if he had committed the specific sin he is afraid he might have committed.