BEIRUT: Imam Musa Sadr – who went missing during a visit to Libya in 1978 – died 20 years later in a prison in Tripoli, a source from the Libyan National Transitional Council has revealed.

“Imam Musa Sadr died in his prison cell where he was being held since his disappearance at the hands of [security] members of the Gadhafi regime in 1978,” the source told local Al-Liwaa newspaper in an interview published Tuesday.

The source said Sadr died from natural causes in the summer of 1998. He was being detained in an underground cell at Tripoli’s central prison, the source added.

His body was kept at the prison’s morgue until the early days of the outbreak of the Libyan revolution, according to the source.

Sadr, the founder of Amal Movement, now headed by Parliament Speaker Nabih Berri, went missing during a visit to Libya on Aug. 31, 1978, along with his two companions – Sheikh Mohammad Yacoub and journalist Abbas Badreddine.

In response to a question about the whereabouts of Sadr’s body, the source said initial investigation conducted by the Libyan interim national council showed that the corpse may have been taken out of the morgue by Gadhafi’s forces to “cover up the crime.”

According to some evidence and accounts of a number of witnesses, the source said Sadr’s body is likely buried in a mass grave that had been recently discovered in a Tripoli suburb.

The Libyan source said the Council has no clue on the whereabouts of Sadr’s two companions.