umm.....what do we do?

I think there is someone squatting in the vacant house next to us! Yesterday Matt started mowing the back yard and there was a dog barking in the back yard next to us. There has never been a dog back there before, where did this dog come from?! I went to our neighbors on the other side of the house thinking maybe there dog dug into the yard, just a thought. It was not theirs. We could see that there was a dog bed in the back yard and a bucket of water. It seems like a nice puppy but it is a pit bull so we did not go in the backyard. Well we fed the dog just in case it needed food and waited to see if it was gone in the morning.
Matt checked this morning and saw that there is a window open facing the back yard. you can see food on the counter and the dog goes in and out of the window, lovely! Well we decided to call the police department and have someone come out to check it out. This is where I get irritated. The cops came (three of them) and knocked on the front door, like someone is going to answer! They then went to the back yard, with there pepper spray ready for the dog, which turned out to be very nice. They said nobody was in the house now but there doesn't seem to be any sign of forced entry! what! the window is open in the back while it is raining. "well nothing is vandalized and everything looks fine, the place needs to be cleaned up a bit but it seems you have new neighbors" that is what the cops said. Yeah right, like new neighbors would drop the dog off and let the dog go in and out through the window! Where did these cops go to school?! This is what we pay for with our tax dollars! They say there is nothing they can do. So I called the realtor and left a message.
*Update....Someone came by to do a home inspection and was startled to find a dog in the back yard. He said that some one did put an offer on the house which was excepted but they would not have the keys yet or be allowed to enter the house till escrow closed, in about 3 weeks.
I hope the dog is taken away and the realtor locks the house up good. Its scary to think someone is possibly squatting there. I am looking forward to having new neighbors though so the house is taken care of. Well that is my vent for the day and I am off to get some acupuncture done, I hope i can relax this time.