Is it permissible to take the agreed-upon amount plus a 10% interest as profit after the agricultural investment has incurred losses, given the suspicion regarding the investor's honesty and his failure to provide sufficient details?

A valid Mudarabah (definition) (profit-sharing) contract is based on a known percentage of the profit, and the loss of capital is borne by its owner. It is not permissible to stipulate a guarantee of the capital or that the Mudarabah be based on a percentage of it. Therefore, an agreement to guarantee the capital and an increase of 10% thereof is void. The loss is solely yours unless it is proven that the worker committed a transgression or was negligent. The default is to accept his word regarding no transgression unless there is clear evidence, and in case of dispute, the matter is referred to the judiciary.