TRIPOLI, Libya — Seif al-Islam el-Qaddafi, facing accusations that he aided his father, Col. Muammar el-Qaddafi, in the brutal suppression of Libya’s uprising three years ago, was not allowed to appear in court in person on Sunday to answer the charges.

A militia in the Libyan mountain town of Zintan has detained Mr. Qaddafi for almost two and a half years, refusing to surrender him to the government. So instead, Mr. Qaddafi’s face — looking sleepy at times, and supremely confident at others — was beamed to the courtroom from a secret location, through a video link. Eight other defendants also took part in the hearing by means of a video link.

Their absence in court underscored the persistent criticisms of the trial by human rights groups, who say the process so far has been marred by the kind of irregularities that have crippled Libya’s judiciary, and dimmed the possibility of a fair process.

On Sunday, another high-profile defendant in the case — Abdullah al-Senussi, Colonel Qaddafi’s feared former intelligence chief — said in court that he was meeting his lawyer for the first time. But the lawyer, Ali al-Dhaba Ali, said he was withdrawing from the case, citing health reasons, which left Mr. Senussi, for the moment, without legal representation.