Christopher Scott Jepsen, who was mistakenly allowed to serve probation following his conviction for a forcible felony, seeks further review after the court of appeals conditionally affirmed his corrected sentence and remanded with directions for the district court to determine whether Jepsen served any of his probationary sentence in a residential treatment facility or an alternative jail facility. See Iowa R. Crim. P. 2.24(5)(b)(providing a defendant is entitled to full credit for any time spent in “custody” in those facilities, but is not entitled to credit for time otherwise spent under supervised probation). Jepsen argues that he is entitled under the Double Jeopardy Clause of the Fifth Amendment to credit against his current sentence of incarceration for the more than four years that he was on probation under an illegal sentence previously imposed on the same offense.