I don't think it's legal for you as a private citizen to go on another person's property to interfere with their dog. Keep trying the humane societies and the local police dept. Send them puctures so they know you are not exaggerating. If you do not get action from those resources, try the HSUS. In the pic you posted it looks like there is a crate the dog can get into. I think that probably qualifies as shelter, and there may be food and water inside it. Or the dog may get fed once or twice a day, it doesn't need to have access to food 24/7. Obviously it does not receive an adequate amount, however, it should not look like that.
Good luck getting help for this dog. Keep taking pictures, keep documenting, and keep records: when you called the humane society and what were the results. Date, time, response. When you called the police, date, time, response, name of person you spoke to, what time they called you back and so on. At some point as someone suggested it may be time to contact your local tv investigative reporter and turn the story over to them, you'll need all this data to support your complaint and get them behind you.
Good luck getting help for this dog. Keep taking pictures, keep documenting, and keep records: when you called the humane society and what were the results. Date, time, response. When you called the police, date, time, response, name of person you spoke to, what time they called you back and so on. At some point as someone suggested it may be time to contact your local tv investigative reporter and turn the story over to them, you'll need all this data to support your complaint and get them behind you.