The hunt for the answer took him from the streets of his childhood in war-torn Lebanon, to an isolation cell in Libya – and to a Tehran on the brink of major war.
In the end, he solved the question, which has resulted in the book "The Hunt for the Missing Imam" and a BBC documentary.
Imam Musa al-Sadr, whose legendary disappearance in 1978 still echoes in the region and is used by top politicians to mobilize supporters, is dead.
How he was probably killed, and why, is described in the book written by Kassem Hamadé together with Theodor Lundgren.
When I decided to write the book, I hoped, and believed, that it would put an end to the Imam's family's suffering. I know how hard it is to live in uncertainty, he says in a video call from Beirut.
Abducted
But powerful forces did their best to prevent the revelation. When Kassem Hamadé traveled to Libya in 2023 to film some final scenes for the documentary about the Imam, he and the BBC team were abducted by intelligence forces linked to the deposed dictator Muammar Gaddafi. Hamadé is convinced that it was to stop his investigative work – and became more motivated than ever to get out his findings.
By then, it had been more than 15 years since Kassem Hamadé, after a tip from an intelligence source in the region, began to investigate the question that was written in his childhood neighborhood.
He was released from the isolation cell after a week, thanks to diplomatic efforts from the United Kingdom, which was involved to help the BBC team. Immediately after, he started working on the book.
Exploited by politicians
When it became clear to those around him that Hamadé was really on his way to publishing the answer to what happened to the Imam, he realized that far from everyone was on his side in the hunt for the truth. One of the threats came from a woman he had long considered a friend.
I have stopped using my car, as a security measure. I take different routes and check them before I go out, he says.
In the end, Kassem Hamadé hopes that the book can lead to people realizing how issues like the Imam's disappearance can be exploited in political games.
They want to turn it into a mystery that no one can solve. I really hope that people become more critical of politicians, of power, and trust journalism more.
Musa al-Sadr was born into a prominent religious family in the holy Iranian city of Qom in 1928.
He moved to Lebanon in the late 1950s and became a central figure for the Shia Muslim population there. In 1974, he founded the political Shia Muslim movement Amal.
Shortly thereafter, the civil war in Lebanon broke out.
When al-Sadr traveled to Libya in 1978, he disappeared.
Since then, the myth about him has led to speculation and political tensions for decades.
Every year, the day he disappeared is commemorated in Lebanon.
The man who succeeded al-Sadr as leader of Amal is today the speaker of the Lebanese parliament, and one of the country's most influential politicians.
