Is a driver who hit a corpse lying on the road obligated to pay blood money and kaffarah (expiation), given that he does not know whether he was the cause of its owner's death or the reason for hitting it?

If two different causes contributing to the damage converge in traffic accidents, then liability falls upon each party responsible according to their percentage of contribution. If their contributions are equal or the percentage is unknown, then the responsibility is borne by both equally. And upon every participant in unintentional killing there is an expiation, even if their percentage (of fault) is less. As for the one whose error is 100%, upon him alone is the expiation, and the blood money is upon his 'aqila (male relatives on the father's side).