How do I get rid of a menace living on my property? Sheriff's won't do anything to get rid of him.?

I have a nightmare living on my property. He's dangerous, loud, destructive and steals everything he can get his hands on. I live in a house in the mountains owned by my mother. She lives nearby. In January she allowed this individual to move his travel trailer to a location behind my house. He was supposed to pay the electric bill every month in exchange for allowing him to live there. My bill was around $200 when he moved in. 2 months later it was $1750. He moved in Jan. 21st and payed $100. The next time I got anything from him was Mid May. He gave me $200 and said he wanted $300 credit because he said my boyfriend owed him $100 because in Jan, while my boyfriend was helping him cut wood, the back window of his truck was accidentally broken by my boyfriend. He has not paid any of the electric bill as per the agreement and he refuses to move. He threatens my boyfriend's life daily, breaks into my house, yells, screams and terrorizes my household, sabotages the pump so we don't have water, severely damaged the pump house (tore the walls out and left it with huge holes you can walk through,steals whatever he can, has pinched my butt and made unwelcome sexual comments to me, tries to hurt my dog, and is generally a nightmare to deal with. He has 10 or so vehicles and lots of tools/junk strewn from one end of the property to the other. All the cars have their hoods/trunks/doors open and most have some or all of the interiors and motors scattered nearby. He refuses to stay out of my immediate living space or move his vehicles and mess to his area. The sheriff has been called twice and they wouldn't do a thing to help. The second time was because He tried to break into the home while we were inside(asleep at 1:15 AM). He was screaming and banging on the doors and walls threatening to kill my boyfriend. By the time the sheriff's arrived he was locked in his trailer, hiding. They didn't talk to him because they said they couldn't just break in as the door was locked. They acted like it was us who are the problem and even went so far as to suggest that WE move!!! We have asked him to pay rent, to be nice, to move out and he absolutely refuses. He was served with a 30 day notice of eviction. I know he will not move. What do I do? How do I get rid of this jerk? We can't afford an attorney. We can't afford to pay the bills, that's why my mom let him move onto the property to begin with! He wanted to help us out! I thought maybe I could get rid of him if I let the power get shut off but the sheriff's told me that if I do that my children will be removed from my home and put in foster care. Can anyone give me any advice about how to fix this situation? I am scared to death of him and afraid he will destroy everything on the property. Thank you for taking the time to read this.