Check at the county courthouse probate court for where the decedent lived to see if possibly anyone has filed to open up probate for the person's estate. If probate has been opened, you can get the name and address of the executor from the file, and then contact the executor to see if he/she has any relevant information. If no probate has been done, you can ask the most closely related surviving next of kin if they know anything about a trust.
DANDY DON IN OKLAHOMA