On August 31, 1978, during a trip to meet Libyan officials in Tripoli, Imam Al Sadr vanished. The imam's supporters believe Qaddafi may have had Al Sadr abducted because of his opposition to Lebanon's civil war.
Fall of Qaddafi may uncover answer to mystery of missing Lebanese imam Mousa Al Sadr
BAALBEK // Hussein Nasrallah was just 10 years old when he stood in a crowd gathered in a Baalbek square to hear a prominent Shiite cleric.
It was 1974, a year before the outbreak of Lebanon's civil war, and Imam Mousa Al Sadr called for unity between the religious sects.
The Iranian-born religious leader went on to found the Amal movement the following year and was seen as a champion of the ordinary Lebanese people.
Then on August 31, 1978, during a trip to meet Libyan officials in Tripoli, Imam Al Sadr vanished.
Now 47, Mr Nasrallah is among those calling for answers to solve this three-decade old mystery.
On Wednesday he joined tens of thousands gathered in the same square where he first heard the cleric speak, for a rally marking 33 years to the day that they believe Imam Al Sadr was kidnapped on the orders of Colonel Muammar Qaddafi.
As Colonel Qaddafi's regime's 42-year grip on power has crumbled, there have been renewed hopes about finding out what happened to Imam Al Sadr.
"I cannot say that he is still alive, but maybe," said Mr Nasrallah, a businessman and father of two. "I have been waiting 33 years for the best moment of my life - when Mousa Al Sadr comes back."
Ties between Lebanon and Libya have been strained since the imam's disappearance. Members of Amal believe the cleric may have been targeted because of his opposition to Lebanon's civil war, which Colonel Qaddafi has been accused of playing a role in.
"We are convinced Qaddafi is the first and last person responsible for this crime," said Ali Diab, a member of the Shiite movement.
For years, there had been little information aboutthe imam, who would now be 83, or his travel companions, Sheikh Mohammed Yacoub and Abbas Badreddine, a journalist.
But, in recent months, conflicting reports have emerged from Libya - some say he is still alive, others that he was killed on Col Qaddafi's orders in 1978. The Qaddafi regime has long maintained that Imam Al Sadr and his aides left Libya for Italy.
A rally in his honour is held every year in Lebanon on August 31, the last day he was seen.
Mr Diab, a member of Amal, said this year's event in Baalbek was one of the largest as supporters wait for "special news".
"They need to know the reality of what happened," he said. "Thirty three years is a long time and now this is a new generation - but they didn't forget about his case."
Although Imam Al Sadr disappeared 15 years before she was born, Amal Muslimani grew up hearing about the cleric.
"Today is a happy and sad day," said the 18-year-old from south Lebanon. "It's sad because he's not with us but we have to prove to Qaddafi that we didn't forget about Mousa Al Sadr."
The cleric's family and supporters remain hopeful that he may still be alive.
"No stone will be left unturned, through both political contacts and judicial efforts, to get to the truth and free the imam and his companions," said Chibli Mallat, the Sadr family's lawyer. "His family firmly believe they are still alive."
While there have been reports in recent days of prisoners escaping or being released after years in Libyan jails, tens of thousands remain unaccounted for.
Mr Mallat, who also teaches at Harvard Law School, said consultations are taking place at the "highest political levels", including with the Libyan rebels' National Transitional Council.
The cleric's supporters are also pressing for a pending Lebanese trial to begin, three years after the country's Higher Judicial Council indicted Col Qaddafi and 16 of his aides in the disappearance of the imam.
The Sadr family's legal team are also looking to the International Criminal Court (ICC), which in June issued an arrest warrant for members of the Qaddafi regime on charges of crimes against humanity.
"When we say 'no stone left unturned', we mean also at the level of the ICC, to highlight the importance of the imam's case," said Mr Mallat.
At the rally on Wednesday, Nabih Berri, the speaker of the Lebanese parliament and Amal's leader, appealed to the NTC to give the case special attention.
"We ask our brothers in the Libyan revolution to make all efforts to investigate and find the location where Imam Al Sadr and his companions were imprisoned, to put an end to this international crime," he said.
"We are sure that in the future we will discover the truth about the crime of kidnapping Imam Mousa Al Sadr."
Seated among the crowd with his family, Mr Nasrallah said he was hopeful about finally learning the truth. "The end of the story is coming. We are sure now that Qaddafi is finished. We just need to know what happened to Mousa Al Sadr," he said.