How do I find proof of assets that are hidden or changed to be under someone else's name rather then my ex- partner.

If I am separate from my partner whose name is under the house and car. And we own a shop in another city. But has recently changed someone else to be the owner of the shop. Overall is hiding the shop. I have no evident on paper to proof but he bought the shop when we were together. We have been married for over 20 years how do I find proof that he owns this shop! And prove that this assets are hidden for court purposes