How should I contact this owner?

[Josephine Wilson]

Newbie question here: There is a SFH I would like to buy and rehab for my mother to live in. The current owner lives OOS and rented it out after his father died. The rent they are charging is about half of market rent. (It was rented to a couple. When the boyfriend moved out, the girlfriend said she could no longer pay the full rent, so the owner halved the rent so she could stay.) The property is one-year past due on property taxes. Interestingly, the property is still claiming a primary residence tax credit, which is not allowed for rentals. Someone could report them, which would raise the property tax bill by 40%.

The property is managed by the current owner's older brother, who is local. He seems to be bad with money because both the father and the father's sister left their property solely to the younger brother. The younger brother inherited five investment properties here, while the older brother owns only his primary residence. 

Reading the tea leaves, the younger brother may be letting his older brother manage and take the income from the dad's house. The older brother may need the money. The younger brother may not know that property tax hasn't been paid. The younger brother may not care if the older brother is too lazy to get a new tenant, but he probably would care that taxes on a property in his name are not being paid. (Incidentally, the older brother is also not paying the tax on his primary residence.)

So I'm wondering what's the best way to convince the younger brother to sell. I'd also be curious if there is other publicly available data I should pull on the house/brothers. Experienced folks will probably say I'm spending way too much time researching a single property, but the location and design of the house is pretty perfect for Mom.