Excellent answers below. That should give you the answer. However, if it doesn't, one thing you can do is knock on neighbors' doors and ask. I've done that a number of times. And if you find a neighbor who's been around for a while, you often can get a lot more information that will be helpful for you to make an offer.
For instance, sometimes I've found properties that are in the condition you describe because an elderly person had lived there, but had died or moved into a nursing home. Even though the tax records may show the person still living there, the property (and the power of attorney) is being managed/handled by one of the owner's children. In another case, it turned out the property owner was in a dispute with the city. He'd moved out of town, but the tax records still showed him residing at the property.
Try your door-knocking at times people are likely to be home--early evening on weekdays, mid-afternoon on weekends. (Avoid mid-day on weekdays, if you can. Women who are home alone are reluctant to answer a door knock from an unknown male.)
Hope that helps.