Canadian police said Friday that they have made three arrests in the slaying of a Sikh separatist leader last June in suburban Vancouver that had become the center of a diplomatic spat with India.

Royal Canadian Mounted Police Assistant Commissioner David Teboul said three suspects have been arrested and charged in the slaying of 45-year-old Hardeep Singh Nijjar by masked gunmen in Surrey, outside Vancouver. But he said police could not comment on the nature of the evidence or the motive. 

“This matter is very much under active investigation,” Teboul said.

The three suspects are Kamalpreet Singh, Karan Brar and Karampreet Singh and were arrested in Edmonton, Alberta, Royal Canadian Mounted Police Superintendent Mandeep Mooker said.

“This investigation does not end here. We are aware that others may have played a role in this homicide and we remain dedicated to finding and arresting each one of these individuals,” Mooker said.

Canadian Prime Minister Justin Trudeau sparked a diplomatic feud with India in September when he said that there were “credible allegations” of Indian involvement in the slaying of Nijjar. India had accused Nijjar of links to terrorism but angrily denied involvement in the slaying. Trudeau said at the G-20 in September that “any involvement of a foreign government in the killing of a Canadian citizen on Canadian soil is an unacceptable violation of our sovereignty.”

Canada recalled 41 of its 62 diplomats from India in October after the Indian government said it would revoke their diplomatic immunity. India suspended visas for Canadian citizens after the murder and issued a travel advisory for Canada, citing security threats against its diplomats there.

U.S. Secretary of State Antony Blinken in September said on the growing tension between Canada and India: “We want to see accountability, and it’s important that the investigation run its course and lead to that result.”

Nijjar, an Indian-born citizen of Canada, was a plumber and also a leader in what remains of a once-strong movement to create an independent Sikh homeland, known as Khalistan. But he had denied allegations of ties to terrorism.

A bloody decadelong Sikh insurgency shook north India in the 1970s and 1980s, until it was crushed in a government crackdown in which thousands of people were killed, including prominent Sikh leaders.

The Khalistan movement has lost much of its political power but still has supporters in the Indian state of Punjab, as well as in the sizable overseas Sikh diaspora. While the active insurgency ended years ago, the Indian government has warned repeatedly that Sikh separatists were trying to make a comeback.