Lurker who lives next door

My father owns a fairly large plot of land in the upstate New York region. For about 2 years, I lived in a trailer on his property. The first year I lived there, I was 16 and living by myself. One night, I came home from a party and I saw a guy walking towards the woods, away from the direction of my trailer. I remember thinking it was odd, but he said "hi, how are you" and I just continued into my trailer and saw no harm in it. <br><br><br>The next weekend or so, I was down by the river with my dog. I noticed a guy coming from my trailer. I thought it was my cousin, but as I got closer I realized it was not. I shouted at him, but he ran away as fast as he could. I didn't think much of it, but the next night I came home and noticed my trailer was open. I walked in to somebody lying in my bed, snoring. I grabbed my baseball bat and put it to his face and turned on the light. It was the guy I saw that night I was by the river and he was the same guy from that night I first saw him walking away from my trailer. I was frozen in fear. My dog, who is a large German Shepherd, was growling as loud as he could. I didn't know what to do, so I yelled at the top of my lungs and hit the guy in the face with my bat. My dog immediately bit the guy and I ran out of the trailer and down to my dads house to call the police. They picked the guy up and nothing ever came of it. They had no idea who he was and he ended up being a squatter who lived in the woods.<br><br><br>I moved out of the trailer and back with my mom a few towns over. I never thought anything of the incident as the police concluded there was no harm intended. I recently moved into the trailer again, and I saw the guy again. He looked older and a little more in shape than before. I called the police immediately and the told me the same thing they told me last time "he doesn't seem to be of harm to anybody".<br><br><br>I'm not sure what to do. I just don't want to come home one night to find him in my trailer again. I cant shell out a huge amount of money to put a whole alarm system on the trailer, and the police really did nothing to help the situation. Any advice would be great.<br><br>EDIT: I don't know how to reply to all the comments, but the police know where to find him and I've since put new locks on all the doors to the trailer. I will also be purchasing mace for me and the girlfriend.