THE Sikh community in Canada is in a state of shock. No one can understand why Mark Vijay Chahal gunned down his estranged wife, Rajwar Gakhal, and eight members of her family. "I am stunned. This has never happened in our community," says Surjit Singh of Toronto. "There must have been something he could have done if he was unhappy. Why kill?" This question is being asked all across the country as Canadians take in the horrific details of the massacre in Vernon, the second-worst mass murder in Canadian history.

On April 4, 30-year-old accountant Mark Chahal left his Burnaby high-rise apartment for Vernon in the western province of British Columbia, home to one of the largest Sikh communities in the country.

In his red Nissan, Chahal was carrying a 12-gauge shotgun and two handguns—a Smith and Wesson 40-calibre semi-automatic pistol and a Smith and Wesson 38-calibre revolver. The entire Gakhal family was in Vernon to celebrate the marriage of Rajwar's younger sister. Rajwar, separated from Chahal for a year, had been...