If the property is in the United States, it may be that your cousin actually perfected title under something called the Doctrine of Adverse Posession. Check with a real estate attorney in the state where the property is located. Most states however require your cousin to actually live in the property or make use of it as an owner. (renting it out qualifies)
You cannot sell the property as it is: your cousin would have to sue for title in court and be awarded that title. Then, and only then, can you get the title insured to sell on the open market. Otherwise, the title is "clouded".
Jul 26, 2012