Re: Preempt
Simple murder is not a federal crime, it's a state crime. That doesn't mean you have somewhere to hide, though, because of extradition laws.
Also, there are ways that a murderer can cause their murder to become a federal crime, but they all involve murder in conjunction with a formal federal issue, such as if a state line is crossed. Here's an interesting writeup on the issue: https://www.wklaw.com/10-ways-murder-becomes-a-federal-crime/