There is no statute of limitations on Crimes Against Humanity. Much more info about statute of limitations for crimes, especially federal crimes.
https://www.jamespaynelaw.com/blog/federal-crimes-statute-of-limitations/
Murder. Both under state and federal law, murder has no statute of limitations, allowing prosecution at any point after the crime.
War crimes. Offenses like genocide, war crimes, and crimes against humanity, prosecuted under laws such as the War Crimes Act of 1996, have no statute of limitations at the federal level.
Yes. See my Post #370.