§ 243. Witnesses not to be excused from testifying. In any criminal
proceeding before a court or grand jury or in any investigation or
inquiry before the common council, or any committee thereof, or before
any officer conducting an investigation, touching the knowledge of such
witness as to any offense committed in violation of the provisions of
this chapter or ordinance of the city; the court or grand jury, or the
common council, committee or officer, may confer immunity in accordance
with the provisions of section 50.20 or 190.40 of the criminal procedure
law; provided, however, that no immunity shall be conferred except upon
twenty-four hours prior written notice to the appropriate district
attorney having an official interest therein.