Amended Penal Code section 1203.067 may not be retroactively applied to sex offender probationer whose offenses were committed prior to September 9, 2010. In 2006 appellant pled guilty to two counts of lewd acts on a child. He was sentenced to 10 years in state prison, with execution suspended, and placed on seven years’ probation. He was subject to the terms and conditions provided in former section 1203.067. On October 19, 2012, over defense objection, the court modified the terms of appellant’s probation in accordance with amendments to section 1203.067. He appealed from the modification order, arguing that amended section 1203.067 should not be applied retroactively in his case. Held: Reversed. Penal Code section 3 provides that no penal statute shall be applied retroactively unless it is clear from extrinsic sources the Legislature intended such application. Amended section 1203.067 was part of Assembly Bill 1844 (Chelsea’s Law), enacted September 9, 2010 as urgency legislation. However, the revisions to section 1203.067 did not become operative until July 2012. Thus, language in the statute applying the amendments to “persons placed on formal probation prior to July 1, 2012,” reflect an intent to apply the law to probationers whose offenses occurred between the law’s effective date and the operative date of changes to section 1203.067, on July 1, 2012. This effectuates the Legislature’s intent to apply the law to probationers whose offenses occurred on or after the effective date of the law. It also avoids serious constitutional questions under the state and federal ex post facto clauses.