Pick over beans and wash them. Soak overnight covered with 2 inches of water. Simmer covered in water until tender. Add tomatoes and continue to simmer. Saute green peppers and onions in oil. Add garlic and transfer to the pot with the beans. Melt butter in a large frying pan and saute meats. Drain fat and add chili powder, salt, and pepper. Transfer to the pot with the beans. Simmer for 1-½ hours, covered.