I think my spouse is hiding assets. What can I do?

This is a potentially expensive proposition. You will likely have to hire a professional to do an asset search. There are people out there called forensics experts and they can search things such as computers (which will probably have to be subpoenaed) to search for deleted, archived and active files which may contain data that would be useful in defending a divorce trial. This type of search would have to be ordered and authorized by the court and is commonly referred to as “electronic discovery.”
But it is not ordered all the time. You have to have compelling reasons to show the court that this type of intrusive search is warranted. A scenario like this occurs with high net worth individuals where one spoyuse is suspected of hiding assets such as bank accounts, businesses, etc.
But this is not a cheap undertaking, so in the average divorce case, it is not going to be a huge issue.
I found this blog on asset search online. You might want to check it out. http://www.assetsearchblog.com/