"They said they would put a bomb in my car," says Professor Zimmerman, head of German studies at the Hebrew University in Jerusalem, who received police protection because of the threats. "One of the leaders of the settlers - the mayor of Kiryat Arba - threatened me openly on television."
Coming six months before the murder of the Israeli Prime Minister, Yitzhak Rabin, the violence of the reaction foreshadowed the growing intolerance of the Israeli right which, Leah Rabin says, set the stage for her husband's assassination.
Nor was the response confined to settlers in the occupied territories. At the Hebrew University itself no less than 79 professors and lecturers took a large advertisement in the press demanding that Professor Zimmerman be fired "for the honour of the Jewish people and for the honour of the university".
Since Mr Rabin's murder the constitutional right has been trying to rebut charges that it tolerated comparisons between the Prime Minister and Nazi leaders. In a notorious poster displayed at a right-wing rally in Jerusalem, his face is superimposed on a picture of Himmler, the author of the Final Solution.
Unsurprisingly, drawing parallels with Hitler's Germany carries an extreme emotional charge in Israel, but it is not unheard of. Ultra-Orthodox Jews in the Me'a She'arim district of Jerusalem used to paint swastikas over the Star of David without creating much comment. Israeli politicians liken people to Nazis as a term of general abuse.
In the interview which started the so-called Zimmerman affair last April, the professor was more specific in his charges. He said: "There is an entire sector of the Jewish public which I unhesitatingly define as a copy of the German Nazis." He says he made his comments on the Hitler Youth after hearing a "radio interview with the children of settlers from Hebron on the first anniversary of the murder of 29 people in a mosque by Baruch Goldstein. The kids said: 'Goldstein is our hero.' "
"These children are trained like the Hitler Jugend to think ideologically without criticism," says Professor Zimmerman. "They are led to believe in racist views of themselves as the master race superior to the Arabs. They even have a song about Ami Popper, an Israeli who killed seven Palestinians four years ago. It goes: 'Ami Popper, Ami Popper, there is nobody like you.' "
Children from Hebron are now one of the three parties taking legal action against the professor, along with Rehavam Ze'evi, the leader of the right- wing Moledet party, and two reserve soldiers serving in a settlement. Somewhat taken aback, the historian says some of his comments were oversimplified - notably an apparent comparison between Israeli soldiers volunteering to serve in the occupied territories and German soldiers volunteering for the SS. Overall, however, he strongly defends his position, saying: "I'm not prepared to duck because several idiots filed charges against me."
Two months before Mr Rabin's death, Professor Zimmerman had also published an article comparing the political situation in Israel with that of the Weimar Republic in Germany in the 1920s. He drew particular attention to the murder in 1922 of Walter Rathenau, the Jewish foreign minister and industrialist, by three young men with links to the army who believed he was betraying the country.
When the Prime Minister was gunned down on 4 November, after addressing a 100,000-strong peace rally in Tel Aviv, Leah Rabin accused the main right-wing party, Likud, of creating an atmosphere of verbal violence. She had not wanted to shake hands with the party's leader Binyamin Netanyahu at her husband's funeral, she said. And she asked where the supporters of peace with the PLO were when its opponents demonised Mr Rabin.
Will the trauma of the assassination change the political atmosphere in Israel? Professor Zimmerman is doubtful. He says none of those who agreed or disagreed with him before the murder have changed their opinions since. National soul-searching about the death has turned out to be Israel's largest spectator sport: everybody is prepared to watch somebody else search their soul. The leader of one right-wing organisation - the Women in Green - has demanded Mrs Rabin apologise for her accusations.
The problem, Professor Zimmerman says, is that "there is a large segment within Israel which legitimises the murder of people, the murder of Arabs by Baruch Goldstein, and even the murder of Jews". They react explosively if compared to the Nazis, but were prepared to tolerate posters identifying Rabin with Himmler. And by that logic, "the death warrant against Rabin was justified".