Federal prosecutors at the Southern District of New York announced charges Wednesday against an Indian government employee for an alleged plot to assassinate an America-based leader of a Sikh separatist movement.

The U.S. attorney for the Southern District of New York, Matthew Olsen, alongside other officials, announced that they were filing murder-for-hire charges against an Indian national, Nikhil Gupta, for his alleged connection to a plot to assassinate an American citizen at New York.

“We will not tolerate efforts to assassinate U.S. citizens on U.S. soil, and stand ready to investigate, thwart, and prosecute anyone who seeks to harm and silence Americans here or abroad,” a U.S. attorney, Damian Williams, said in a statement.

Mr. Gupta was arrested in the Czech Republic on drug trafficking charges at the request of the American government in late June and has since been detained. The murder-for-hire charges were brought against him in a superseding indictment unsealed Wednesday.

Mr. Olsen said in a statement that “dedicated law enforcement agents and prosecutors in this case foiled and exposed a dangerous plot to assassinate a U.S. citizen on U.S. soil.”

“The Department of Justice will be relentless in using the full reach of our authorities to pursue accountability for lethal plotting emanating from overseas,” Mr. Olsen said.

Mr. Gupta is an Indian national and is accused of being involved in international narcotics and weapons trafficking. The indictment also references an unnamed Indian government employee who describes himself as a “senior field officer” with “security management” and “intelligence” responsibilities.

Authorities say that the unnamed official who allegedly orchestrated the assassination plot references himself in documents as having served in India’s Central Reserve Police Force. 

This may be only one of many plots, according to investigators. One of these plots, investigators allege, surrounded the murder of a Sikh separatist leader, Hardeep Singh Nijjar, who was killed in June outside of a Sikh temple in British Columbia.

The day after the murder of Nijjar, authorities report that Mr. Gupta told the undercover assassin that Nijjar “was also the target” and “we have so many targets,” before adding that there was “now no need to wait” on killing the target at New York City.

In September, Prime Minister Trudeau said that there were “credible allegations” linking the Indian government to Nijjar’s death. Nijjar was a Canadian citizen.

The allegation led to the expulsion of diplomats from both countries and tensions between Canada and India have since escalated.