In People v. Collins (1996), 45 Cal. App. 4th at pages 864-865, the defendant entered into a plea bargain agreement in the juvenile court in which he expressly agreed to participate with law enforcement and the prosecution in a murder case. In return, the prosecution reduced the charge against defendant from murder to accessory after the fact, and the court agreed to a juvenile commitment to the California Youth Authority. The express agreement was conditioned on defendant continuing to participate in the murder case, including giving truthful testimony. Defendant admitted the truth of the allegations in the amended petition under section 602 of the Welfare and Institutions Code and, following a disposition hearing, was committed to the California Youth Authority for five years. After defendant had been committed to the Youth Authority, the prosecution asserted that he had breached the plea agreement by giving false testimony at a preliminary hearing for another person. The juvenile court set aside the plea bargain and reinstated the original section 602 petition. An indictment was then returned charging defendant with a number of felonies, including special circumstances murder and perjury. Defendant was found unfit for juvenile court and his case was handled in the adult court. Ultimately, defendant pleaded no contest to voluntary manslaughter and a number of other felonies. His previous commitment to the Youth Authority was vacated and he was sentenced to state prison for 21 years. One of the issues raised on appeal was that the trial court lacked jurisdiction to consider the prosecution's motion to resume proceedings against him since his sentence had already gone into effect. The court in Collins found that the trial court had jurisdiction to enforce the terms of a plea bargain and therefore had jurisdiction to vacate a judgment in the event of a breach of a plea bargain even after the sentence had gone into effect. (People v. Collins, supra, 45 Cal. App. 4th at pp. 863-864.) The court also held that even if the trial court lacked the power to act upon a motion to vacate a plea bargain after sentence had commenced because it would be an act in excess of jurisdiction, the defendant was estopped to raise or assert the trial court's lack of jurisdiction due to his participation in and agreement with the terms of the plea bargain which contemplated further proceedings after sentencing. (Ibid.)