LEV52 A person is obligated to return anything that he has stolen. 1) If a person has stolen something, kept back wages, or failed to return an object he was asked to guard, or a lost object he has found, there is a positive Torah commandment which obligates him to return it. Although this verse explicitly refers to someone who denies under oath that he has stolen, the commandment to return that which was stolen applies to every instance when someone illegally possesses that which belongs to another person. (Chinuch and Minchas Chinuch, 130). If the stolen object was not altered from its original state, the object itself must be returned. If the object was lost or altered (for example, someone stole wool and dyed it), the monetary value of the stolen object in its original state must be returned. (ibid). 2) Whenever you are obligated to give money to someone, you must pay him even if he is unaware of your obligation. The Chofetz Chayim writes that whenever a question concerning financial matters arise, a person should consult a halachic authority. He should not rely on his own judgment, since a person will usually be lenient in judging his own financial obligations. (Mishnah Brurah 606:1). 3) If the victim of a theft did not realize that anything was stolen, the thief does not have to inform him about it. He fulfills his obligation by returning the money by mail, even if he does not sign his name or explain why the money is being sent. He must, however, be sure that the victim receives the letter (for example, he can send a registered letter or send the money with a messenger who will not reveal the identity of the sender). (Rabbi Moshe Feinstein in Igros Moshe, Choshen Mishpot, 88). 4) If the victim was aware of the theft, and thereby suffered anguish, the thief must ask his forgiveness. Ideally, he should ask for forgiveness in person or write a signed letter. But if this is too difficult, at least he should send an unsigned letter stating that he is returning money that he stole, and that he regrets his theft and asks forgiveness. (ibid.) 5) if someone stole and does not know the identity of the person from whom he stole, he must give money for something that is used by the public (Bava Kama 94b; Choshen Mishpot 366:2). The reason behind this is that the victim might benefit from the money. Therefore, the money maybe given only for something the public will use; the money may not be given to any individual. Building and repairing a mikvah (ritual bath) is considered a need of the public and is recommended as the means to repent for stealing when the victim's identity is not known (Igros Moshe, Choshen Mishpot 88).