Haunted house?

So, the remodeling is STILL coming along.....slowly. But an interesting thing is happening to us. 4 different times over the past couple of weeks we've noticed that someone is either coming into our house at night with a key.....or.....our house is haunted. I'm pretty much thinking its the later, but you never can tell. Here's the facts: I'm at the house most afternoons doing stuff plus keeping an eye on the workers. At the end of the day, either Alex or I will shut off all the lights and lock ALL the doors. But, despite this, we have come back the following day and find that one of doors is unlocked or ajar and sometimes a light is on in the house. Most recently this happened on Wednesday morning. I was there all day on Tuesday, locked up and shut the lights off. On Wednesday morning I went to check on the house because it had rained very heavy the night before. When I went down to the basement, I opened the door and found that all the lights were on. I quick, backed out and then high-tailed it out of there. I checked the doors upstairs and found the front door unlocked. UGHHHHH! So who can it be you ask? So do we? We haven't changed the locks yet because we wanted to wait until after the house was finished, right before we move it. So, obviously its someone who still has a key......or its the lady that died in the house! I went to the local police dept to ask them if they could drive by at night and keep an eye on it and the cop I spoke to mentioned that THEY had a key! Then he went back to a HUGE panel box...........FULL of keys! It was like they had a key for every house in our town! How small town is that?! But, in the end he couldn't find it. Hmmmmm?!

So, I've told Alex that we need to get the locks re-keyed NOW! Thats my project for today.....after that we can really decide if its a person that is curious or a ghost that is curious......I hope its not the ghost!