What is the ruling on money gained by a person from a sham business deal, which he had entered into with another person who was managing it, and he did not discover the reality of the fraud and deception in it until it was too late?

If the intended benefit is to obtain money equal to or less than the invested capital, then there is no blame on the recipient because he has recovered his capital. However, if the intention is to obtain fictitious profits that exceed the invested capital, then this excess amount is not due to the recipient and must be returned to the other depositors, because it is not a profit from a real trade.