Cal. Penal Code § 1001.72

(a) If the defendant consents and waives his or her right to a speedy trial, the case shall be referred to the probation department. The probation department shall conduct an investigation as is necessary to determine whether the defendant qualifies for diversion under this chapter, and whether he or she is a person who would be benefited by education, treatment, or rehabilitation. The probation department shall also determine which education, treatment, or rehabilitative plan would benefit the defendant. The probation department shall report its findings and recommendations to the court. If the recommendation includes referral to a community program, the report shall contain a statement regarding the program’s willingness to accept the defendant and the manner in which the services they offer can assist the defendant in completing the diversion program successfully.
(b) No statement, or any information procured therefrom, made by the defendant to any probation officer, which is made during the course of any investigation conducted by the probation department pursuant to subdivision (a), and prior to the reporting of the probation department’s findings and recommendations to the court, shall be admissible in any action or proceeding brought subsequent to the investigation.
No statement, or any information procured therefrom, with respect to the specific offense with which the defendant is charged which is made to any probation officer subsequent to the granting of diversion, shall be admissible in any action or proceeding.
In the event that diversion is either denied or is subsequently revoked once it has been granted, neither the probation investigation nor statements or information divulged during that investigation shall be used in any pretrial sentencing procedures.