(a) Whenever in the judgment of the Attorney General or any district attorney the testimony of any person or the production of evidence of any kind by any person in any criminal proceeding before a court or grand jury is necessary to the public interest, the Attorney General or the district attorney may request the superior court in writing to order that person to testify or produce the evidence. Upon order of the court that person shall not be excused on the basis of his privilege against self-incrimination from testifying or producing any evidence required; but no testimony or other evidence required under the order or any information directly or indirectly derived from such testimony or evidence may be used against the person in any proceedings or prosecution for a crime or offense concerning which he testified or produced evidence under court order. However, he may nevertheless be prosecuted or subjected to penalty or forfeiture for any perjury, false swearing, or contempt committed in testifying or failing to testify, or in producing or failing to produce evidence in accordance with the order but shall not be required to produce evidence that can be used in any other courts, including federal courts. Any order entered under this Code section shall be entered of record in the minutes of the court so as to afford a permanent record thereof; and any testimony given by a person pursuant to such order shall be transcribed and filed for permanent record in the office of the clerk of the court.

(b) If a person refuses to testify after being granted immunity from prosecution and after being ordered to testify as aforesaid, he may be adjudged in contempt and committed to the county jail until such time as he purges himself of contempt by testifying as ordered without regard to the expiration of the grand jury. If the grand jury before which he was ordered to testify has been dissolved, he may purge himself by testifying before the court.