In 2011, tens of thousands of people took to the streets of Yemen to demand the resignation of President Ali Abdullah Saleh. The protesters called not only for extensive political change but also for the president to be held accountable for the human rights abuses and other crimes he committed during his decades-long political career. One of the issues Yemenis wanted Saleh to answer for was the 1977 assassination of the president of North Yemen, Ibrahim al-Hamdi.

Al-Hamdi, viewed by many as a reformer and modernist, came to power in a bloodless coup in June 1974, when Yemen was divided into two countries: North Yemen, supported by Saudi Arabia and the United States, and South Yemen, supported by the Soviet Union. During his short tenure as head of state, al-Hamdi instituted several reforms to fight corruption and establish an egalitarian system, earning the public’s support and respect. He also implemented policies aimed at reducing his country’s dependence on Saudi Arabia and attempted to unify the North and the South.

In October 1977, just two days before a scheduled visit to South Yemen to negotiate unification, al-Hamdi was assassinated. The exact circumstances of his death remain a mystery to this day.

Vice President and Army Chief of Staff Ahmad al-Ghashmi, who succeeded al-Hamdi as president, claimed at the time that al-Hamdi was killed in a murder-suicide involving his brother Abdullah and two French prostitutes. While officials refused to reveal the details of al-Hamdi’s death, it was widely rumoured that the bullet-ridden corpses of the president, his brother and two French women were found in a flat in Sanaa that belonged to one of the women.

Al-Hamdi’s family and political allies, however, never accepted the bizarre story as told by al-Ghashmi and the rumours that followed. Instead, they believed the president was assassinated by al-Ghashmi and his ally and eventual successor, Saleh. They also argued that the French women were added to the story simply to damage al-Hamdi’s reputation. There were several witnesses who came forward to say that the president was invited to al-Ghashmi’s house on the day of his murder and was last seen alive inside the home in the company of al-Ghashmi and Saleh. The Yemeni public also overwhelmingly believed that the president was killed by his political adversaries, mourning him as a respected national hero.

Despite the claims, questions and accusations surrounding al-Hamdi’s assassination, there has never been an official investigation into the circumstances of his death. Al-Ghashmi was himself assassinated in June 1978 before answering any questions about the death of his predecessor. Saleh, who took over the presidency in July 1978, also refused to talk about al-Hamdi’s death during his time in power.

This is why, in 2011, when people took to the streets to protest against the excesses and abuses of President Saleh’s government, some were carrying large posters of al-Hamdi. Young activists, most of whom were not even born when the tragedy occurred, were chanting slogans demanding justice for the reformist president, because they viewed his assassination as a breaking point in their country’s history.

Saleh was forced to resign in November 2011, but the overthrow of the president did not stop Yemenis from demanding answers about the murder of al-Hamdi. In 2016, Saleh finally addressed the issue in an interview with the RT network and denied playing any role in the killing. Nevertheless, he revealed that the official story pointing to a “sexual scandal” was completely fabricated, and claimed that agents paid by Saudi Arabia staged the assassination. Saleh later threatened to continue to talk about Yemen’s past political crimes, but he was killed in December 2017 before revealing anything more about al-Hamdi’s assassination.

In April 2019, an investigative documentary by Al Jazeera, titled Yemen: The Last Lunch, traced the events leading up to al-Hamdi’s murder using official documents, witness reports and expert testimonies. Beyond answering questions about who might have carried out the assassination, and how, the documentary also explored the possible motivations behind the crime.

Explaining how al-Hamdi’s efforts to make his country a strong, independent actor in the southern Red Sea region by building a strong economy and uniting with South Yemen disturbed the Saudi leadership, the documentary added weight to Saleh’s assertion that Riyadh was behind the assassination. The film also presented several other reasons why Saudi Arabia opposed the presidency of al-Hamdi: His policy to diminish the political influence of tribes in Yemen; his marginalisation of the Hashid tribe’s Paramount Sheikh Abdullah bin Hussayn al-Ahmar, who was a top agent of Saudi Arabia in Yemen; and his refusal to settle a border issue with Saudi Arabia, which had existed since the 1930s when the kingdom conquered three provinces of North Yemen and arranged a decades-long lease to keep possession.

Al Jazeera’s documentary clearly showed that Saudi Arabia had strong motivations for eliminating al-Hamdi at the time. But no one has yet provided indisputable proof that Riyadh was behind the assassination. Moreover, it is widely believed that it was impossible for Saudi Arabia to carry out a plot to assassinate the president of Yemen inside his own territory without assistance from powerful local players.

Yemen’s former presidents, al-Ghashmi and Saleh, were perhaps the only two people who were in a position to shed light on al-Hamdi’s murder. As they are both gone, finding out exactly what happened to the reformist president who wanted to unite Yemen and make it an independent powerhouse in the Middle East appears to be an impossible task.

As Yemen’s devastating civil war enters its fifth year, the mystery surrounding the death of al-Hamdi continues to loom over Yemenis’ collective political memory. If and when the country succeeds in leaving the conflict behind, any post-war government will face the difficult task of uniting a divided nation and gaining the trust of all its citizens. By launching an official investigation into al-Hamdi’s death and revealing the people and powers behind his murder, the future leaders of Yemen could help the nation heal. Moreover, such an investigation can help Yemenis see the powers that hinder their country’s development and encourage them to take collective action to stop history from repeating itself.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.