A Kansas attorney may be able to give you better advice for what works in your jurisdiction. For estates that both my Firm and I have handled, you generally will locate assets by a couple of different ways, all of which can be time consuming. You will want to look through all of the records of the decedent that you can find, take your letters of administration to each of the institutions that you knew the decedent had accounts at and see if you can get back records of each of the accounts (to see where the old administrator moved the money), and you can also talk to the old advisors of the decedent to see if they can help you out with any information on the decedent's assets.
Ultimately though, I have had the most success with hiring a private investigator who specializes in lost asset searches. I would recommend that you contact several private investigators in your area to see if any have that specialty. Note as well that many of them charge varying rates for this service, so you will want to shop around to find one that will not overcharge you for the service.
Good luck with your case.
When looking for assets in KS I always start by pulling a credit report on the deceased individual. The credit report will often list any open bank accounts, credit lines, etc. Next I look at the tax returns, and specifically Schedules B and D, to find any receipts of interest, dividends or capital gains. I also review all available statements/records at the decedent's residence.
If I still think there are assets out there that I have not been able to locate, I will call an investigator who specializes in that type of work. As a last resort - if your state has an unclaimed property fund, check to see if the decedent's name appears in their database. Good luck.
It is quite possible that the previous administrator has already liquidated assets and (hopefully) deposited them in an estate account. Therefore, you may wish to expand your search for assets in the name of "John Doe, as Administrator" and "Estate of Jane Doe" as well as in the name of the decedent individually. You may have to contact individual financial institutions. Checking the unclaimed fund database is a good idea. Finally, the IRS might be willing to provide certain information if no fiduciary returns have been filed. It is not an easy process to locate assets under these conditions.