First of all, aside from any biohazard/enviornmental claim, many jurisdictions require disclosure of any deaths that occurred on the property. If you were not so informed, whether intentional or not, you most likely have the right to cancel the transaction and receive a refund of your deposit (and quite possiblity any out of pocker expenses such as inspection fees and the like). What you need to do now is to contact a local real estate atorrney in your area; when you do be sure to bring a copy of your contract with you so that they can review it.