Canadian police charged three Indian nationals on Friday with first-degree murder in the death of a prominent Sikh activist and said officers are actively investigating links to Prime Minister Narendra Modi’s government.

The murder of Hardeep Singh Nijjar in Surrey, British Columbia, last year sparked a major diplomatic clash between India and Canada. Prime Minister Justin Trudeau accused Modi’s administration of orchestrating the killing, prompting India to dismiss the allegation as "absurd” and expel dozens of Canadian diplomats.

The Royal Canadian Mounted Police revealed Friday that three Indian citizens living in Edmonton had been arrested. Karan Brar and Kamalpreet Singh, both 22, and Karanpreet Singh, 28, have each been charged with first-degree murder and conspiracy to commit murder.