Owner Died state wont sell

There is a house I would love to buy, it has been vacant for 5 years. I spoke with the neighbors and was told the lady died 5yrs ago and it has sat ever since. I contacted the D.C. government about the owner and they said they were looking for next of kin. However, I have searched and searched and cannot find any. Also the lady was a senior citizen and was exempt from property taxes so the property will not be auctioned off for taxes. I dont know what my next step would be, can anyone help? Thanx