Section 939.2 Of Article 4. Conduct Of Investigations From California Penal Code >> Title 4. >> Part 2. >> Chapter 3. >> Article 4.
939.2
. A subpoena requiring the attendance of a witness before the
grand jury may be signed and issued by the district attorney, his
investigator or, upon request of the grand jury, by any judge of the
superior court, for witnesses in the state, in support of the
prosecution, for those witnesses whose testimony, in his opinion is
material in an investigation before the grand jury, and for such
other witnesses as the grand jury, upon an investigation pending
before them, may direct.