What is the ruling on using ill-gotten money to build a toilet or a path to the mosque?

If a person possesses ill-gotten wealth due to usurpation, theft, or similar acts, they are obligated to return it to its owner or their heirs. If they are unable to identify the owner or reach them after making diligent effort, they should give it away in charity on their behalf. If the owner is later found and ratifies the charity, that is permissible. Otherwise, the person must give the owner their due, and they will receive the reward for the charity. As for what was taken with the owner's consent through bribes or corrupt contracts, it must be disposed of by spending it on general Muslim welfare.