We have already learned (daf 103) that a person who steals and swears falsely, denying the theft, must pay back the amount he stole plus and additional penalty of one fifth. Our Mishna (108b-109a) teaches that if a person stole from his father and then denies it under oath, in the event that his father dies, he must pay back the other descendants who inherit his father.
According to Rashi and other commentaries, in this case, the thief will lose his share in the inheritance when he pays back the stolen money. If he does not want to lose his share, the Mishna has a suggestion – he can borrow money from a third party who will come and collect it. The Me’iri explains that this is permitted in order to ensure that he does not retain the actual money that he stole, so we find a method that will allow him to “launder” the money. This concern appears in the Gemara, as well, where Rav Yosef suggests that if he is the only person who will inherit, he should turn the money over to charity; according to Rav Papa, he should even announce that the charity money is money that he stole from his father.
According to the Rambam, the Mishna never suggests that someone will lose his share of the inheritance, since his share belongs to him and cannot be taken away. The point of the Mishna is that the money that was stolen cannot remain in his possession and must be transferred to someone else, leaving him to get his share of the inheritance from other moneys. In the event that he does not have brothers who are set to inherit, then he must find some other way of moving the money out of his possession, e.g. by paying off a loan or giving charity – as long as he does not retain his ill-gotten gains (see Rambam Hilkhot Gezelah 8:2-3).