Also among the defendants are Abdullah Senussi, Col Gaddafi's brother-in-law and security chief, Abuzeid Dorda, his head of intelligence, and Baghdadi al-Mahmoudi, his prime minister. Mr Senussi spoke to denounce his treatment by the authorities, saying he had been able to appoint defence lawyers only five days before and they had not been allowed in court.
Wearing a blue prison uniform like the rest of the defendants, and with sunken cheeks and close-cropped hair, Mr Senussi appears very different from his days in power, when his tightly curled black hair, fierce expression and muscular presence marked him out instantly in the photographs where he would be shown at the right hand of the leader.
In total, 23 of the 37 defendants were in court. Seven are being held in the city of Misrata to the east of Tripoli, and as with Saif al-Islam ``security reasons'' were given for not bringing them to Tripoli. The other six were not publicly accounted for, though one defence lawyer said that four were believed to be on bail and not to have been given notice of the hearing.
Whatever the legalities, the lack of security reflects Libya's continuing crisis, three years after the revolution. Much of the country is controlled by regional militias, which refuse to submit to central authority. The government itself is torn between Islamists who control the parliament, the general national congress, and more secular politicians who have the backing of the West.
The handling of the case against Col Gaddafi's former associates and sons has been criticised by human rights groups, who point out that Libya said it was competent to conduct a fair hearing when it refused to hand over Saif al-Islam Gaddafi and Mr Senussi to the International Criminal Court in The Hague, where they have both been indicted for war crimes.
The ICC has rejected that argument in the case of Saif al-Islam, partly on the grounds that he is not being held under central judicial authority, though it accepted it in the case of Mr Senussi, a decision against which his international legal team is appealing.
The trial is being held in a special court inside the al-Hadba prison in western Tripoli where the highest-profile prisoners are being held, a pastel-painted block bedecked with the new red, green and black revolutionary flags.
Prison officials, who are said to answer to the defence ministry rather than the justice ministry, refused to allow relations, some lawyers and some journalists inside for the hearing, without giving a reason. The court sat for 40 minutes, ruling that the defence should be allowed to see but not copy prosecution documents. The case was adjourned to April 27.