If the assassination of Prime Minister Hariri confirmed anything about the Middle East, it was the hunger of its people for accountability. The old tactics of extrajudicial killings, which may have intimidated people into silence in the past, are now creating the opposite effect.

Tehran, too, is struggling with its own case of extrajudicial killing – one that simply will not go away, as so many had in the past. It is the case of Zahra Kazemi, the Canadian-Iranian journalist, who died while in custody in 2003, and whose body was never returned to her family. In the ensuing trial, a lower-level official was acquitted of any wrongdoing. The verdict enraged Canada, who withdrew its ambassador to Tehran, and disheartened yet another nation hungry to see justice served. One among the disheartened was Shahram Azam, an Iranian-trained physician who had examined Kazemi when she was brought to his emergency room. He fled Iran a few months ago to seek asylum in Canada. In a historic press conference this April, he presented a damning file and personal testimony to the causes of Kazemi’s death: brutal rape and torture.

Why should the world shift its attention from Iran’s nuclear threat to the Kazemi case? Because the last time the world did so, it helped usher in the reform era. The year was 1997. The month: April. And the case that spurred it all was called the Mykonos trial.

After four years, several hundred sessions and witnesses, thousands of pages of documentary evidence, the Superior Court of Justice of Berlin implicated top Iranian leaders in the 1992 murders of several Kurdish leaders at the Mykonos Restaurant in Berlin. Judge Frithjof Kubsch ruled that the murders had been ordered by Iran’s Committee for Special Operations to which Ayatollah Rafsanjani, Iran’s president at the time, and Ayatollah Khamenei, the spiritual leader, belonged. An international arrest warrant was issued for Ali Fallahian, the intelligence minister, for his role in the assassinations. It was a rare moment in modern history when leaders, who were still in power, were accused of murder.

The verdict came weeks before Iran’s presidential elections, at a time when the polls showed the moderate candidate, Khatami, behind the hard-line Nateq Nouri. After the verdict, all the European Union members, with the exception of Italy, recalled their ambassadors and shut down their embassies in Iran. An unprecedented isolation enveloped Tehran. Until then, the regime had explained its lack of relations with the United States as a diplomatic exception. With the departure of the European Union, the exception became the rule.

The architects of the Khatami campaign immediately seized the opportunity to reinvent their candidate as the president who would reunite Iran with the international community and create “a dialogue among civilizations.” The verdict, the single most important foreign factor to influence the elections, was the way Europe answered the call of the Iranian students who were demanding rule of law and civil society.

Mykonos also showed that if the world delivers justice to Iran, Iranians will deliver the rest. Unlike the Chinese student leaders of Tiananmen who fled China, the Iranian students leaders still live in Iran, though some are languishing in prisons. Unlike China, Iran, named the fifth most corrupt government by the watchdog “Transparency International,” cannot derail political reform by spurring economic boom. The aspiration for reform is alive. So are the students to carry it out.

In 2003, Europe honored the Iranian human-rights lawyer, Shirin Ebadi, with the Nobel Peace Prize. Once again, Europe stood with the people of Iran in their quest for justice. Now, it is time to match the glory with actions. The Mykonos trial was an exception among tens of murders in which the court dared to fully investigate the cases. The overwhelming majority of them never went as far as the Mykonos trial did: They punished the henchmen, but not the masterminds.

We are standing at the threshold of a moment very much similar to that of Mykonos. It’s April. The new round of presidential elections will be held in June. The world wants to contribute to Iran’s struggle for democracy, especially in a nonviolent way. A key witness has come forth. Canada and its allies can come together in the way that the E.U. did in 1997: Follow in the footsteps of Judge Kubsch. Deal a blow to the tyrants who caused Kazemi’s death.

If the international community does so, this time the Iranian presidential elections are likely to finish what began in 1997. No other act will be a greater boost to the cause of reform, or bring about a swifter transition.

Ms. Hakakian is co-founder of Iran Human Rights Documentation Center and the author of “Journey from the Land of No: A Girlhood Caught in Revolutionary Iran” (Crown).