Lab. Code, § 6315

(a) There is within the division a Bureau of Investigations. The bureau is responsible for directing accident investigations involving violations of standards, orders, special orders, or Section 25910 of the Health and Safety Code, in which there is a serious injury to five or more employees, death, or request for prosecution by a division representative. The bureau shall review inspection reports involving a serious violation where there have been serious injuries to one to four employees or a serious exposure, and may investigate those cases in which the bureau finds criminal violations may have occurred. The bureau is responsible for preparing cases for the purpose of prosecution, including evidence and findings.

(b) The division shall provide the bureau with all of the following:

(1) All initial accident reports.

(2) The division’s inspection report for any inspection involving a serious violation where there is a fatality, and the reports necessary for the bureau’s review required pursuant to subdivision (a).

(3) Any other documents in the possession of the division requested by the bureau for its review or investigation of any case or which the division determines will be helpful to the bureau in its investigation of the case.

(c) The supervisor of the bureau is the administrative chief of the bureau, and shall be an attorney.

(d) The bureau shall be staffed by as many attorneys and investigators as are necessary to carry out the purposes of this chapter. To the extent possible, the attorneys and investigators shall be experienced in criminal law.

(e) The supervisor of the bureau and bureau representatives designated by the supervisor have a right of access to all places of employment necessary to the investigation, may collect any evidence or samples they deem necessary to an investigation, and have all of the powers enumerated in Section 6314.

(f) The supervisor of the bureau and bureau representatives designated by the supervisor may serve all processes and notices throughout the state.

(g) In any case where the bureau is required to conduct an investigation, and in which there is a serious injury or death, the results of the investigation shall be referred in a timely manner by the bureau to the appropriate prosecuting authority having jurisdiction for appropriate action, unless the bureau determines that there is legally insufficient evidence of a violation of the law. If the bureau determines that there is legally insufficient evidence of a violation of the law, the bureau shall notify the appropriate prosecuting authority, if the prosecuting authority requests notice.

(h) The bureau may communicate with the appropriate prosecuting authority at any time the bureau deems appropriate.

(i) Upon the request of a county district attorney, the department may develop a protocol for the referral of cases that may involve criminal conduct to the appropriate prosecuting authority in lieu of or in cooperation with an investigation by the bureau. The protocol shall provide for the voluntary acceptance of referrals after a review of the case by the prosecuting authority. In cases accepted for investigation by the prosecuting authority, the protocol shall provide for cooperation between the prosecuting authority, the division, and the bureau. Where a referral is declined by the prosecuting authority, the bureau shall comply with subdivisions (a) to (h), inclusive.