California Code, Labor Code - LAB § 5701

The appeals board may, with or without notice to either party, cause testimony to be taken, or inspection of the premises where the injury occurred to be made, or the timebooks and payroll of the employer to be examined by any member of the board or a workers' compensation judge appointed by the appeals board. The appeals board may also from time to time direct any employee claiming compensation to be examined by a regular physician. The testimony so taken and the results of any inspection or examination shall be reported to the appeals board for its consideration.