Cal. Lab. Code § 5707

If the body of a deceased employee is not in the custody of the coroner, the appeals board may authorize the performance of such autopsy and, if necessary, the exhumation of the body therefor. If the dependents, or a majority thereof, of any such deceased employee, having the custody of the body refuse to allow the autopsy, it shall not be performed. In such case, upon the hearing of any application for compensation it is a disputable presumption that the injury or death was not due to causes entitling the claimants to benefits under this division.