Dear Mr. Chattaraj,
Why not and abosutely it is one's wish and view to invest and gain profits as business for the sake of his personal growth, provided he is satisfied in his investment which he risks for which he reaps as its returns.
In my opinion, the investor should do either one of the following at his will to authenticate his investment and his returns:
1. Act as a financier/ Investor to fund the project with the promised returns based on the project report provided by the firm, written agreed and signed by both the parties, with an exclusive Arbitration Clause with its jurisdiction added to it.
2. Enter himself into the partnership firm as one of the active partner and oversee all the activities which the firm does as regards the project to have a better control of his investment.