Does a person on a tourist visa have the legal capacity to sign a business contract?

If you have real reason to believe that your business partner is hiding funds and trying to sell the business behind your back the best course of action may be to file suit against the partner and seek a court order enjoining them from transferring the business. You could also likely get an order forcing your partner to account and potentially removing your partner from control of the business. A foreign citizen can own an interest in an American company, so the fact that they are in the country on a tourist visa is probably not going to have an impact here. With the tourist visa they wouldn't be able to get a job, but I don't think it would create an issue with business ownership. In any event it would be an immigration issue and wouldn't likely have an impact on your dealings. Please feel free to follow up if you have questions. Jon