The Madras High Court on Monday asked the Tamil Nadu government why it could not hand over the inquiry into the police firing at protestors in Thoothukudi to the Central Bureau of Investigation, PTI reported.

The bench of Chief Justice Indira Banerjee and Justice PT Asha was hearing petitions seeking a court-monitored investigation into the firing that took place in May. The court asked officials to submit all documents and material related to the violence and firing by July 9.

Thirteen people agitating against the expansion of the Vedanta Group’s Sterlite Copper plant in the coastal town were killed in firing by security personnel on May 22 and 23. The police have transferred the case to the Crime Investigation Department.

In a counter affidavit, Thoothukudi Superintendent of Police Murali Rambha said the investigation by the CID was progressing in a “fair and impartial manner” and there was no need for a CBI inquiry. He said the Supreme Court had observed on many occasions that courts must impose limitations on themselves while considering pleas asking for a CBI inquiry.

Rambha said a one-man commission of inquiry had also been set up to look into the incident. He opposed the plea to file murder cases against revenue officials who issued the order to fire, and said the officers had complied with lawful orders issued by the competent authority to uphold public order.

The chief justice had earlier said that since the state police was involved, the CBI should look into the matter, reported NDTV.