Police had opened fire to beat back the protesters where 13 people were killed, causing national outrage and the subsequent closure of the Sterlite Copper plant in May 2018 for alleged pollution.

The Central Bureau of Investigation has framed charges on 17 counts, including damage to public property and possession of deadly weapons, one of the sources said. These charges carry a maximum penalty of up to seven years in prison. The charges have not yet been made public.

The law enforcement agency was yet to comment on the matter. One policeman has also been charged, a second source said, without providing additional details. Witnesses had said that police opened fire without warning in violation of the police manual, prompting demands from political parties in Tamil Nadu that police officers be held accountable.

The environmental protest was the deadliest in India in a decade. A working group of United Nations’ human rights experts condemned the “apparent excessive and disproportionate use of lethal force by police.”

Twelve of the protesters were killed with shots to the head and chest, autopsy reports later showed. Police previously said they were overwhelmed and opened fire because they feared the protesters were about to attack people in government offices.