What recourse do I have against someone who stole property from me and what proof do I need?

My sister's boyfriend asked to live temporarily in my house until he could get himself together after she recently passed away. He moved out about 6 weeks later without my knowledge taking the appliances (value about $600) from the property and left unpaid past due utility bills (about $300). He admitted to the theft. But refuses to return them. He says that he and my sister built a life together. He is unemployed other than day labor type jobs. FYI...She paid the rent, the utilities, the household bills and supplied the food. He paid zero dollars toward her funeral. Instead, I had to pay the entire cost. What can I do about this?