Do the owners of stolen or usurped money have a right to the future salary or fruit of the educated person, if these funds were used to finance his studies? And is this money earned from knowledge considered development of the usurped money?

The difference between spending usurped money and investing it is that if usurped money is invested, there is a known dispute regarding its profit, as mentioned in the fatwas. However, if it is spent on oneself, or on education, or similar things, the money is destroyed, and the usurper's liability is established. If it was a fungible item, its like must be returned. If it was a non-fungible item, its value must be returned, with a dispute concerning the exact day on which the value is to be considered. If the usurped item is destroyed, the fungible item is guaranteed by its like, and the non-fungible item by its value on the day it was destroyed in the place of its usurpation. If it is mixed with the usurper's money in a way that it cannot be distinguished, its like becomes obligatory upon him. If it was not a fungible item, he guarantees it by its value on the day it was destroyed in the place of its usurpation, in its currency. The same applies to every item destroyed without usurpation, or seized through an invalid contract.