Is my partner liable for losses with me in a business deal if I am solely responsible for its management and follow-up?

The jurists agree that the hand of a partner over the company's funds is a hand of trust (amanah), and trusts are not guaranteed except in cases of transgression or negligence. So, if the questioner has fulfilled his duty of due diligence and has not been negligent in the procedures, then he is not liable. However, if he has fallen short in his duty and has caused the dealing with a fictitious company, then he is liable and bears the loss alone.