The first conviction was tossed out on a technicality, and the second was overturned in 1992, when the Supreme Court of Canada found that the law was an unreasonable limit on freedom of expression.
Mr. Zündel, who moved to Canada from Germany as a teenager, was twice denied Canadian citizenship. In 2000 he moved to the United States, where he ran a website and lived with his third wife, Ingrid Rimland.
In 2003, American authorities arrested Mr. Zündel for overstaying his visa. He was sent back to Canada, but the authorities there did not want him. They detained him as a threat to national security, given his ties to neo-Nazi groups, a decision that drew criticism from some civil liberties advocates.
After another lengthy legal process, Mr. Zündel was deported to Germany in 2005. A state court in Mannheim, after yet another tumultuous trial, convicted him in 2007 on 14 counts of inciting hatred and one count of violating the memory of the dead. (A member of his defense team, Sylvia Stolz, was jailed and disbarred for signing “Heil Hitler” on a legal document.)
Mr. Zündel was sentenced to five years in prison but released in 2010, partly in consideration of his time spent in pretrial detention.
Recently, Mr. Zündel petitioned the American authorities to allow him to travel to Tennessee to care for his wife, who is 81. The administrative appeals office of the Department of Homeland Security denied his request on March 31.
“The record shows that the Applicant is a historical revisionist and denier of the Holocaust, distributing writings, books, tapes, videos and broadcasts to promote his views,” the office found. “The record indicates further that these publications agitated for aggressive behavior against Jews. Furthermore, the Applicant has been a leader in these activities for decades and has shown no regret or remorse for his actions.”
On Monday, the Center for Israel and Jewish Affairs, Canada’s leading Jewish advocacy organization, said in a statement: “Ernst Zündel’s death brings to a close an especially pernicious saga that plagued Canadians for decades.”
In a phone interview, Bernie M. Farber, who was the chief executive of the Canadian Jewish Congress, now part of the Center for Israel and Jewish Affairs, said that “for decades, he was the gasoline that fed Holocaust denial” in Canada.
Mr. Farber, now the executive director of the Mosaic Institute in Toronto, added, “He was…