Tracking down heirs

[Chris Rosenberg]

Hello all. Someone told me about a property in which the owner died recently. They really didn't have any additional info. So I went there and knocked on some neighbors' doors. I was able to speak to a neighbor who gave me the scoop. Apparently the heirs are 2 grand nieces who live out of state. They have not visited the house since the owner passed away 2 weeks ago. I informed the neighbor that I was very interested in buying the house and asked if there was any way she knew how to get in touch with the heirs. She didn't, so I left my phone number with her. I also left a personal letter in the mailbox stating my intentions. I mailed a letter too, in case they had a forwarding address. I looked online and found a list of relatives of the deceased. I think I found one of the heirs who has a social media account. 

So what do you think is the next step? Should I try speaking to more neighbors, contact the heir directly through social media (at least who I think is the heir), or should I just be patient and wait and see? Thanks in advance for all replies