Except as provided in subsection (b) of this section, if the Attorney General determines that an investigation conducted under § 6–602 of this subtitle provides sufficient grounds for the prosecution of a criminal offense discovered in the course of the investigation, the Attorney General shall have exclusive authority to prosecute the offense. The Attorney General, in the Attorney General’s discretion, may prosecute a police–involved incident not otherwise within the investigative jurisdiction of the Division under § 6–602(c) of this subtitle if the incident is referred by a State’s Attorney to the Attorney General for prosecution. A State’s Attorney may prosecute a criminal offense described in subsection (a)(1) of this section only if the Attorney General requests that the State’s Attorney prosecute the offense.