Saddam Hussein and one of his co-defendants have refused to provide handwriting samples for experts to authenticate signatures said to be theirs on key documents in their trial, the chief judge said Wednesday.

Handwriting experts had been due to testify Wednesday in the trial, but they did not show up at court, forcing chief judge Raouf Abdel-Rahman to adjourn until Monday after a session that lasted only about five minutes.

Prosecutors told Abdel-Rahman the analysts had not yet finished their work. Saddam and his seven co-defendants did not attend the session.

The documents, presented by the prosecution during the six-month-old trial, concern a crackdown on Shiites launched by Saddam's security forces after an assassination attempt on the former leader in the town of Dujail in 1982. Among them is a document said to be signed by Saddam approving death sentences for 148 Shiites, as well as numerous memos and letters from the Mukhabarat intelligence agency and Saddam's office.

Saddam and the former members of his regime face a possible death sentence if convicted over the deaths of the 148 Shiites, as well as the imprisonment of hundreds of others, some of whom say they were tortured.

Saddam has refused to confirm or deny whether some of the signatures are his, while some of his co-defendants have outright said their alleged signatures on the documents are forgeries.

Abdel-Rahman said during Wednesday's session that Saddam and co-defendant Barzan Ibrahim — Saddam's half brother and the former head of the Mukhabarat — had so far refused an order to provide writing samples.

Still, he appeared surprised when the experts did not appear. "They were supposed to come," he said, telling the prosecutors, "You as the prosecution general are supposed to inform the experts to come. Legally, it's your duty to do so."

Prosecutors have nearly finished presenting their case in the trial. The defense is due to present its arguments in upcoming sessions. Abdel-Rahman told defense attorneys Wednesday they must present a list of witnesses they intend to call by Sunday.

U.S. officials observing the trial have said the five-member panel of judges could issue a verdict and sentence as soon as June.

Saddam has acknowledged ordering the 148 Shiites put on trial before the Revolutionary Court that sentenced them to death. But he and his co-defendants have argued their actions were justified because they were responding to the assassination attempt against the former Iraqi leader.

The prosecution has sought to show that the crackdown went far beyond those involved in the attack and sought to punish the entire town of Dujail. They have presented documents showing entire families — including women and children — were among those imprisoned for years and that children as young as 11 were among those sentenced to death.

Dujail residents — including women — have testified in court that they were tortured with electrical shocks and beatings during their interrogations.

In the meantime, the tribunal is preparing to launch a second trial of Saddam — along with six other co-defendants — on genocide charges in connection with the military's Anfal Campaign against Kurds in the 1980s that killed an estimated 100,000 people. They would likely face a death sentence in that trial, as well.