A person received a parcel in the mail on Pesach. It is chametz. It turns out that the mailman accidentally brought to his house a parcel that was meant for his neighbor, a non-religious Jew. The neighbor comes knocking on the door and asks: Did you get my parcel? What should he do? Hand the chametz to his Jewish neighbor? Lie?
He can’t give it to his neighbor on Pesach, as that is lifnei eiver, and he also has to throw it out. Regarding how to handle his neighbor, he could tell him that he doesn’t have it, (throw it out beforehand) and he will compensate him for it.