How do I get someone from my past to stop contacting me?

Have you been charged with a crime? This is the criminal defense forum and this question does not appear to belong here. Perhaps you can get a civil injunction. Go see a local attorney about this.

Unless you have sufficient grounds and want to pursue some type of restraining order, there is little more you can do to make someone stop contacting you through Facebook. Social media is a public event for anyone. There is really no way to stop someone from creating a new account. Wish I had better news, but your options are very limited.

You need to report the contact to the police to document the unwanted contact. Start with talking to a police officer and having them tell the person to knock it off and leave you alone. If that doesn't work, the officer may be able to write up enough reports to convince the district attorney to charge them with harassment. Harassment can be physical (hitting someone), telephonic (calling someone repeatedly or electronic (email or Facebook). You aren't eligible for a Family Abuse Prevention restraining order under Oregon law. Your only other option is to consider a stalking order. You would need to show that there has been more than one "unwanted contact" and that this has caused you enough alarm that you fear for your safety. When you talk to the police, you may inquire about a stalking order but keep in mind they're difficult to get and if you obtain one, it can be contested and difficult to keep in place. The courts hold stalking order to a pretty high burden of proof because they're permanent and can trigger felony convictions and prison time if violated repeatedly.