OPINION
¶ 1 Clarence William Helmer petitions this court to review the trial court’s summary dismissal of his petition for post-conviction relief. He argues the court erred by dismissing his petition because his sentence for failing to timely register as a sex offender pursuant to Arizona Revised Statutes (“A.R.S.”) section 13-3821 (Supp.1998) violates constitutional bans against ex post facto laws. Specifically, he contends that because he committed the offense before the legisla *310 ture changed the crime from a class six to a class four felony, thereby increasing the sentence for offenders, the court erred by refusing to sentence him for committing a class six felony.
¶2 To resolve Helmer’s appeal, we must decide whether the offense of failing to register as a sex offender is complete upon an offender’s initial failure to timely register his status, or whether the violation is a continuing offense. For the reasons that follow, we decide the offense is a continuing one. Because Helmer continued to fail to register as a sex offender after the legislature designated the crime as a class four felony, the trial court did not err by sentencing him under that classification. Thus, although we grant review of Helmer’s petition, we deny relief.
BACKGROUND
¶3 In 1996, an Oklahoma court convicted Helmer of two counts of sexual abuse by a caretaker. The court sentenced Helmer to nine years’ imprisonment on each count, but then suspended these sentences except as to the first twelve months, during which time he was to be held in the county jail. Upon completion of the twelve month sentence, he was placed on supervised probation. Helmer was released from supervised probation in March, 1998.
¶ 4 On March 16, 1998, Helmer moved to La Paz County, Arizona, and resided there at all times pertinent to this action. Pursuant to A.R.S. § 13-382KA) (Supp.1997), Helmer was required to register as a sex offender with the La Paz County sheriff within ten days “after entering and remaining” in the county, which he failed to do. As of March 16, 1998, a person who violated § 13-3821(A) was guilty of a class six felony. A.R.S. §' 13-3824 (Supp.1997). Effective August 21,1998, however, the legislature amended § 13-3824 and made failure to comply with the sex offender registration requirements a class four felony. 1998 Ariz. Sess. Laws, ch. 291, § 3.
¶ 5 On June 6, 2000, the State indicted Helmer on one count of failing to register as a sex offender from March 16, 1998 through June 4, 2000, in violation of A.R.S. §§ 13-3821 and -3824. The State designated the offense as a class four felony. Helmer pled guilty to the charge on August 21, 2000, and the trial court sentenced him to an aggravated prison term of three years.
¶ 6 In post-conviction-relief proceedings, Helmer argued the court erred by sentencing him based on his conviction of a class four felony rather than a class six felony. He therefore asked the court to resentence him. The court denied relief to Helmer, and his petition to this court followed.
DISCUSSION
¶ 7 The
ex post facto
provisions of the Arizona and federal constitutions
1
prohibit our government from enacting laws that increase the penalty for a previously committed crime.
See State v. Noble,
¶ 8 In contrast to the instantaneous nature of most crimes, a “continuing offense” endures over a period of time, and its commission is ongoing until cessation of the proscribed conduct.
Wright v. Super. Ct.,
15
*311
Cal.4th 521,
¶9 Although the legislature did not expressly state that a violation of the registration requirements of § 13-3821 constitutes a continuing offense, the language of that provision reflects this intention. First, with exceptions,
2
a person required to register under that provision must do so for life.
State v. Lammie,
¶ 10 The nature of the registration requirements also supports a conclusion that the legislature intended a violation of § 13-3821 to be a continuing offense. Section 13-3821(G) requires a registrant to give identifying information to the sheriff, including all names by which the person is known. The sheriff is directed to fingerprint and photograph the person and send copies together with the other information submitted by the registrant to the criminal identification section within the department of public safety and the chief of police, if any, of the registrant’s community. A.R.S. § 13-3821(G). As previously described, supra ¶ 9, the registrant is required to annually provide updated information to the motor vehicle division.
¶ 11 Our supreme court has stated that these registration requirements serve a regulatory purpose by giving law enforcement a current record of the identity and location of registrants.
Noble,
¶ 12 In summary, we hold that the explicit language of A.R.S. § 13-3821 and the nature of the crime involved evidence the legislature’s intention that a violation of that provision is a continuing offense that achieves finality only when the offender satisfies the prescribed registration requirements.
3
Because Helmer continued to violate § 13-3821 after the legislature had designated it a class four felony, the court did not violate
ex post facto
principles by sentencing him for committing a class four felony.
See Wright,
CONCLUSION
¶ 13 For the foregoing reasons, we grant review of Helmer’s petition for review but deny relief. We hold that the offense of failing to register as a sex offender under A.R.S. § 13-3821 is a continuing offense. Therefore, the trial court did not violate the ex post facto provisions of the state and federal constitutions by punishing Helmer for committing a class four felony even though the crime was designated a class six felony at the time Helmer initially violated § 13-3821 by failing to timely register.
Notes
. The Arizona Constitution provides that "[n]o ... ex-post-facto law ... shall ever be enacted.” Ariz. Const. art. 2, § 25. The United States Constitution provides that ”[n]o State shall ... pass any ... ex post facto Law____" U.S. Const. art. I, § 10, cl. 1. We interpret the
ex post facto
clause in the Arizona Constitution similarly to the
ex post facto
clause in the United States Constitution.
State v. Noble,
. Any duty of juvenile offenders to register terminates when the person reaches the age of twenty-five years. A.R.S. § 13-3821(D),(F) (Supp.2000). A person required to register because of a conviction for unlawfully imprisoning or kidnapping a minor is only required to register for a period of ten years from the date he or she completes the terms of the imposed sentence. A.R.S. § 13-3821(K).
. Other courts have reached similar decisions.
See State v. Goldberg,
