NEW DELHI — Hardeep Singh Nijjar, a Sikh independence advocate whose killing two months ago is at the center of a widening breach between India and Canada, was called a human rights activist by Sikh organizations and a criminal by India’s government.

Canadian Prime Minister Justin Trudeau said Monday that his government was investigating “credible allegations” that Indian government agents were linked to the June 18 slaying, when Nijjar was gunned down outside a Sikh cultural center in Surrey, British Columbia.

India has denied any role in the killing, calling the allegations absurd.

A Separatist and a Plumber in Canada

Nijjar, 45 when he died, was a prominent member of a movement to create an independent Sikh homeland known as Khalistan, and was organizing an unofficial referendum among the Sikh diaspora with the organization Sikhs For Justice.

He also owned a plumbing business and served as president of a Sikh temple or gurdwara in suburban Vancouver, where banners hung with his face promoting the referendum on Tuesday. In a 2016 interview with the Vancouver Sun he responded dismissively to reports in Indian media that he was suspected of leading a terrorist cell.

Following his death, the World Sikh Organization of Canada called Nijjar an outspoken supporter of Khalistan who “often led peaceful protests against the violation of human rights actively taking place in India and in support of Khalistan.”

India Called Him a Militant; He Denied It

Nijjar was a wanted man in India, which has for years seen Sikh separatists abroad as a security threat.

In 2016, Indian media reported that Nijjar was suspected of masterminding a bombing in the Sikh-majority state of Punjab and training terrorists in a small city southeast of Vancouver. He denied the allegations.

Last year, Indian authorities accused Nijjar of involvement in an alleged attack on a Hindu priest in India and announced a reward of about $16,000 for information leading to his arrest.

India’s War Against Separatism

The modern Sikh independence movement reaches back to the 1940s but eventually became an armed insurgency that shook the country in the 1970s and 1980s. In 1984, then-Prime Minister Indira Gandhi ordered a raid to capture armed separatists taking refuge in Sikhism’s holiest shrine.

More recently, the Hindu nationalist-led government of Prime Minister Narendra Modi has cracked down on both non-Hindu rights movements and dissidents.

Sikh diaspora activism has been a source of tension between India and Canada for years. Canada has the largest population of Sikhs outside India, and India has repeatedly accused it of tolerating “terrorists and extremists.”

Nijjar Was Shot at a Temple

Canadian police said Nijjar was shot as he was leaving the parking lot of the Sikh temple where he served as president in British Columbia. He suffered multiple gunshot wounds and died at the scene.

After the killing, a lawyer and spokesperson for Sikhs For Justice, Gurpatwant Singh Pannun, said Nijjar had been a target of threats because of his activism. His killing was the second in two years of a prominent member of the Sikh community in Canada.

Canada’s Sikh Community Rallies Behind Him

Nearly a week after Nijjar’s slaying, about 200 protesters from Canada’s Sikh community gathered in front of the Indian Consulate in Vancouver to demonstrate. Many of the protesters were convinced that Nijjar’s killing was linked to his calls for an independent Sikh state.

On Monday, Moninder Singh, a spokesperson for the British Columbia Sikh Gurdwara Council, told Canada’s CTV that the wave of support for Nijjar seen after his death was an indication of how he was seen in the community.

“The community is shattered. There are very, very high emotions,” Sukh Dhaliwal, a member of Parliament who represents Surrey, said days after the killing.