Are you paying for the property out of your pocket or are you borrowing money (whether a mortgage or a private investor) to help purchase the property? Your question is a little vague and tough to decipher. Providing more details would assist us in answering your question.
It is quite possible that the (1) investor is the guarantor of the original mortgage or (2) a single or group of participating bank(s). Loan participation was quite common a few years ago, pre-2008, where banks would pool together and take a percentage of the loan. This minimized exposure of each individual bank and provided diversification. It was also common among smaller banks with lending limits that prevented them from doing the transaction unless they pooled their lending limit with other banks. In those situations, the lead lender handled the negotiations and facilitated communications between the loan participants.