Where the names and addresses of possible witnesses have been furnished to the coroner by the next of kin of the deceased, an attorney for the next of kin, or the district attorney, the coroner shall, if it reasonably appears to him that the persons named are in fact necessary witnesses, subpoena such persons to appear at the inquest hearing.
Source:
Section 27499.1, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=27499.1..