It was one of the most harrowing attacks in recent Canadian history. Alek Minassian plowed into pedestrians on a busy section of Yonge Street in Toronto with a rented van, killing 10 and wounding 16. Just before his attack on Facebook, he wrote of an 'incel rebellion,' aligning himself with the ideology of involuntarily celibate men who blame women for the fact they are alone. Minassian has admitted he carried out the attack. But this week, as he faces trial for murder and attempted murder, his lawyers are expected to argue that their client was not criminally responsible for his actions. CBC's Ioanna Roumeliotis tells us how it could unfold.