As a public school teacher in nearby Eckville, Keegstra spread his anti-Semitism to a captive audience in the Eckville public schools for years with hardly any complaints. When his lies were exposed, many in the community came to his defense. He was even Mayor for a time.
Keegstra was the classic fundamentalist Christian anti-Semite. He learned his anti-Semitism from crackpot Christian tracts like The Talmud Unmasked. Keegstra taught his students all sorts of nonsense, from the claim that John Wilkes Booth was Jewish, to Illuminati conspiracies, to the claim that Jews killed Franklin Roosevelt and that they were behind all kinds of world disasters, to Holocaust denial --- and his students duly repeated these claims in their essays. (One student essay contained the line "we must get rid of every living Jew so that we can live in peace and freedom.")
It was only when some courageous parents finally spoke out against Keegstra that the school board took action. It was actually his anti-Catholicism that got initially got him noticed; echoing today's crackpot claims of Rebecca Bynum and Jody Hice about Islam, Keegstra claimed that Catholicism was not a religion but a "humanly created ideology". In 1982 he was finally suspended from teaching. Later, he was prosecuted under Canada's hate speech laws. (Personally, I think the prosecutions were misguided; they only served to make Keegstra more of a martyr. He should not have been teaching his pernicious lies in the public schools, but neither should he have been convicted for believing them.)
If you would like to know more about Keegstra, a good source is Bercuson and Wertheimer's book A Trust Betrayed: The Keegstra Affair.
Believe it or not, there are people who praised Keegstra. For example, Joshua Blakeney, a former Alberta graduate student who was actually awarded a Queen Elizabeth II graduate scholarship for his bizarre "investigations", tweeted a recommendation of this Press TV article eulogizing Keegstra. (Warning: you're likely to want to wash your hands after clicking the link.) In case you didn't know, Press TV is a propaganda arm of the Iranian government. Blakeney is, by the way, also heavily into 9/11 conspiracies. Blakeney was a student of Lethbridge professor Anthony Hall, whose reasoning ability can be gauged from this article.