As you correctly note, there is little, if anything, you can do in Nebraska as the person sending the messages is overseas. As to your question, "Are there any chances I can secure my Facebook so I don't receive any messages from anyone except my friends?" this is not a legal question but a question about Facebook itself. I believe you can limit who can send you messages in Facebook. You might also be able to report the threats and harassing messages to Facebook, which can block the messages or remove the person from Facebook. I would look into Facebook's Help Center as well as read Facebook's Terms and Policies.
Answered on Oct 11th, 2012 at 1:18 AM