You may have seen 20/20 or one of the other investigative programs covering property fraud. This could either be someone pretending to sell a property that is currently unoccupied and not belonging to the fraudulent "sellers" or some other scheme which involves recording a document at the County Clerk's Office attempting to show that the property is being transferred to them (unknown to the property owners).
To protect your property you can sign up at Property Fraud Alert and they will inform you if someone tries to record a document with your name shown. Some counties provide the service free. If not, there is a fee. You can check on their site to see if your state/county is included. Find more information here
I received the flyer below in with my property tax appraisal. Tarrant county offers Property Fraud Alert service free.