Have you posted Lost Dog signs? Often dogs wander (run) miles from their home, so he might not belong to anyone in your neighbors . If the people are looking for him, they will be calling shelters, vets, and animal control. He looks like a mix of Shepherd (face coloring) , boxer (head shape, body color) and terrier (small feet) but that's just a wild guess. I hope you find his family or that he finds a new family with you:0) We tried keeping a second dog who needed us (she was 14 years old and her owner had died, the retired daughter couldn't keep her). We had Brownie for 7 months until Valentine's Day of last year when I had no choice but to put her down because she was failing miserably and my hubby was in the hospital with life-threatening issues. Our golden (a rescue dog) didn't like playing second fiddle; his normally good behavior became a problem for 7 months and showed me that not all dogs who are great alone can give up their throne.
Here's praying that signs work wonders. LOL