Need Ex husband advice?

My ex husband is a registered offender, and I have had to press charges on him before for menacing and stalking. Our daughter was adopted out when she was 4 days old, but a few years after I left him, her parents agreed to let me have a relationship with her. Now she is almost 16 and he is talking to her online. I have talked to her parents twice, which got me nothing but her mad at me and my ex threatening me, he even went as far as threatening to kill me right on his facebook page! My daughter refuses to stop talking to him, and lies to me about talking to him at all. How do I get her to understand how dangerous he is? He's threatening to kill me, and she seems to think its funny. I think he is telling her a lot of lies about me, but she won't talk to me about any of it because I called her parents to let them know what was going on. I don't know what else to do to protect her, and I am talking to the sherrif about getting a civil protection order against him. Any thoughts, or ideas?