The Saint-Jean hit-and-run driver, Martin Couture-Rouleau, appeared on a list of 90 persons monitored by Canadian police and had been identified as a “high-risk traveler”; He was arrested last summer when he tried to leave the country for the Middle East. Official sources have not said anything about whether Couture-Rouleau and the Ottawa shooter, Michael Zehaf-Bibeau, were acquainted or connected in any way. Former Public Safety Minister Stockwell Day, however, told The Daily Beast on Wednesday that the two men may have visited the same Internet chat rooms. ISIS has promoted using cars as weapons against Westerners, though it remains unclear whether Couture-Rouleau drew inspiration from the extremist group.

Since 2006, Canadian security has thwarted many localized plots—two in 2013 alone. At a July 1 Canada Day celebration in front of the British Columbia legislature, two Canadian-born converts to Islam intended to detonate homemade pressure-cooker bombs, police charge. Two non-citizens—one Palestinian, one Tunisian—were arrested in April 2013 for allegedly plotting to derail a passenger train.

A lot of energy is wasted debating whether do-it-yourself jihadists should be called “terrorists.” The Obama administration notoriously insisted on describing the Ford Hood shooting of 2009 as an incident of “workplace violence,” not terrorism. The killer at Fort Hood, Major Nidal Malik Hassan, was perceived by colleagues as mentally troubled long before he opened fire, killing 13 and wounding 32 more. Judging by media reports, Zehaf-Bibeau likewise could be described, if one wished to eschew the T-word, as a troubled misfit with a long record of petty criminality. On the other hand, what kind of person would one expect jihadists to recruit from inside a Western society? In countries like Canada, Australia, Britain, and the United States, the call to Islamic holy war often appeals to more marginal people: the thwarted, the troubled, the angry. And yet even so, the Saint-Jean killer—Couture-Rouleau—reportedly had a clean police record and a reasonably stable personal life until his conversion to Islam. He owned a pressure-washing business and lived in a single family home with his father.

If you are alienated, angry, and attracted to violence, radical Islam provides a powerful ideology of justification. If you are lonely and purposeless, it offers redemptive self-sacrifice (one report claims that Couture-Rouleau persuaded “four or five” friends to convert to Islam with him). Until roughly 1960, French-speaking Quebec ranked as one of the most Catholic societies on earth. In the late 1950s, more than 80 percent of French Quebeckers could be found at Mass on Sundays, according to one famous estimate. Then, abruptly, in the short span of years from 1960 to 1980, religion seemed almost to vanish from the province. It’s been aptly said that from the point of view of religious observance, “centuries, not decades” separated the Quebec of the 1980s from the Quebec of the 1950s. Yet the hunger for meaning is always a part of the human spirit. In a different time, Couture-Rouleau might have vanished into a monastery. In the 21st century, he found a different and deadlier path. The alleged would-be British Columbian bombers might likewise have gravitated to Maoism in the 1960s or Nazism in the 1930s. But those ideologies too have lost their hold on the modern mind, leaving radical Islam as the strongest competitor for the credence of those who seek self-fulfillment through mass destruction.