Cal. PEN § 1191.25

The prosecution shall make a good faith attempt to notify any victim of a crime which was committed by, or is alleged to have been committed by, an in-custody informant, as defined in subdivision (a) of Section 1127a, within a reasonable time before the in-custody informant is called to testify. The notice shall include information concerning the prosecution’s intention to offer the in-custody informant a modification or reduction in sentence or dismissal of the case or early parole in exchange for the in-custody informant’s testimony in another case. The notification or attempt to notify the victim shall be made prior to the commencement of the trial in which the in-custody informant is to testify where the intention to call him or her is known at that time, but in no case shall the notice be made later than the time the in-custody informant is called to the stand.

Nothing contained in this section is intended to affect the right of the people and the defendant to an expeditious disposition of a criminal proceeding, as provided in Section 1050. The victim of any case alleged to have been committed by the in-custody informant may exercise his or her right to appear at the sentencing of the in-custody informant pursuant to Section 1191.1, but the victim shall not have a right to intervene in the trial in which the in-custody informant is called to testify.