Tripoli, Libya (CNN) -- The second son of former Libyan leader Moammar Gadhafi appeared via a video link Sunday at his trial at a court in Tripoli, where he and dozens of former senior regime officials face charges for crimes they are accused of committing during the 2011 revolution.
Saif al-Islam Gadhafi, once his father's heir apparent, has been held in the western mountain city of Zintan by the militiamen who captured him in 2011. The group has refused to hand him over to the central government, citing security concerns and lawlessness in the capital.
The trial was held under tight security with roads leading to Tripoli's al-Hadba prison blocked off by security forces and gunmen positioned on the building's rooftop.
The judge read the charges against the defendants, which included the killing of protesters -- a crime punishable by a death sentence -- and other alleged crimes to try and suppress the 2011 uprising.
Among the 23 defendants present at the hearing were Abdullah al-Senussi, the elder Gadhafi's brother-in-law and former spy chief, former Prime Minister al-Baghdadi al-Mahmoudi and the regime's head of foreign intelligence, Buzeid Durda. Eight other defendants held in the city of Misrata also appeared via video link at the trial.
After more than two years in prison, Senussi, who was extradited from Mauritania, appeared frail and had lost weight.
Gadhafi seemed relaxed and frequently smiled during the two-hour proceeding. In response to the judge's question on whether he had a lawyer, Gadhafi responded twice, saying, "I have God". He later said he did not have a lawyer, and the court ordered one to be appointed for him.
The International Criminal Court in the Hague indicted Gadhafi and Senussi on war crimes, but Libya refused to hand them over, arguing they had to face justice in their own country.
Although the international court granted Libya the right to try Senussi last year, his ICC-appointed lawyer was appealing the ruling.
Some defendants complained about not having enough access to their lawyers, and Senussi asked the court to allow foreign lawyers to represent him because Libyan lawyers, he said, were not able to do so.
Rights groups have raised concerns about Libya's ability to provide the defendants with a fair trial.
"The case of 30+ former Gadhafi officials has been problematic from a procedural point of view from the onset as some defendants, including Saif al-Islam Gadhafi and Abdullah Senussi, both held in isolation in different locations, still do not have access to a lawyer and were not able to review court documents," said Hanan Salah, a Libya researcher for Human Rights Watch. "In cases involving the death penalty, it is more important than ever to adhere to fair trial standards."
There have also been concerns about the use of the video link in this trial.
"Every defendant should have the right to communicate and consult without delay and in full confidentiality with their lawyers before and during a trial. The current arrangements in which some defendants are physically separated from the court and their lawyers cast doubt over respect for these rights and some defendants risk being mere spectators in their own trial," said Salah, who was observing Sunday's proceedings in Tripoli.
The judge adjourned the trial to May 11.