Of the murders and killers that are and have been in Canada, Clifford Olsen and Marc Lepine could possibly some of the worst in Canadian history. Clifford Olsen was a serial killer who was targeting kids of both genders in the Vancouver area while Marc Lepine was a Mass Murderer who over the course of about 20 minutes gunned down both women and men (the target being women) at the École Polytechnique at the University of Montreal.
Clifford Olsen began his criminal behavior quite early on in life, commiting B&E's and thefts, etc. He was even a nuisance in prison, "buggering" the younger inmates in prison, and blabbing to the authorities about anyone doing anything, making him quickly unpopular among inmates and guards, which led to solitary confinement. When he was out of prison, he started targeting kids of both sexes, sexually assaulted them, and hid there bodies all over Vancouver and neighboring communities. After being charged with the murder of one of the victims, he made a full confession, even offering to sell the bodies for cash, the deal being he would give the location for each body for $10 000, or altogether, all of them for $100 000, the 11th body being a "freebie". I believe that the reason he commited these murders was due to his behavior when he was younger, this can be backed up from the fact that he favored Sexually Assaulting young inmates.
Marc Lepine was a young man who had been bullied or laughed at most of his life. In 1989, at the engineering school
École Polytechnique at the University of Montreal, he entered a classroom, fired 2 shots, and asked the men to leave the room, and ordered the women to line up against the wall. After explaining that he hated feminism, he shot the women, from left to right. Over a period of around 20 minutes, he shot several men and women over several different areas of the school, and when a fire alarm was pulled, shot himself in the head, killing himself.
The biggest question here is, can we stop people from committing crimes of this magnitude in Canada, and how so? In my opinion, we can't. Most criminals learn there behavior from when they are very young, and there is no possible way we can watch every single youth in Canada 24/7 to make sure they aren't being assaulted, being the assaultie, or being in some way shape or form, being involved in Criminal activity, whether it be from being a victim or a perpetrator. We can however, learn from these behaviors. We could research other criminal behaviors, and compare their crimes, etc to Marc Lepine and Clifford Olsen, and look for similar traits and actions vs. the crimes committed, and in this way look for similarities to see if there's similar reasons or something that might trigger something in their brains to make them commit these crimes.