Responsa על בבא קמא 237:4

(3) As an apostate, L forfeits her rights as an heir, even though she has the power to transmit her property to her Jewish heirs. Although it is not known whether L apostatized after her parents were killed, it is legally assumed that she has apostatized after their death. Nonetheless, L's heirs cannot acquire L's property and rights of an heir, during the latter's lifetime, since the above mentioned assumption does not devolve for the benefit of her heirs. The disputed property should be retained by A, and C's heirs, inasmuch as they are in possession of this property.

Q - A deposited money with B for safekeeping. A died and was survived by a son C, who later apostatized. Must B return the money to C?
A - There is a difference of opinion regarding property of an apostate. I maintain, however, that A should continue to safeguard it, awaiting the time that C might repent and return to the fold. It is not directly permissible for B to spend the money or seize it for his personal use. However, if B had already done so, it can no longer be exacted by judicial process.
If C had never returned to Judaism, but died, the money should be returned to his Jewish heirs, since it is the unanimous opinion of the Rabbis, that an apostate retains the power to transmit his property to his Jewish heirs. If B wants to act with equity, he should return the money to C's Jewish heirs, after C's death, even if B had spent the money or seized it for his personal use.