Is there an ex post facto violation in a new sex offender crime imposed on an offender who failed to register?

A similar issue was addressed in Russell v. Gregoire (9th Cir. 1997) 124 F.3d 1079, which found no ex post facto violation in the new crime imposed on an offender, convicted prior to the passage of the sex registry act, who fails to register. "We emphasize that the crime of failing to register under the Act constitutes a separate offense. The fact that a prior conviction for sexual misconduct is an element of the `failure to register' offense is of no consequence. It is hornbook law that no ex post facto problem occurs when the legislature creates a new offense that includes a prior conviction as an element of the offense, as long as the other relevant conduct took place after the law was passed." (Id. at pp. 1088-1089.)