A criminal expert's report was read out in court on Monday, saying Saddam's signatures were on documents connecting him with the killing of 148 Shia men and teenagers after an attempt on his life in the town of Dujail in 1982.
Saddam and his half-brother and former intelligence chief have refused to give the Iraqi tribunal in Baghdad a sample of their handwriting.
Khamis al-Ubaidi, one of Saddam's lawyers, requested the court to appoint other experts, saying those testifying were members of the interior ministry.
He said: "They cannot be independent when they have links to the interior ministry and the state."
Raouf Abd al-Rahman, the chief judge, adjourned the trial until Wednesday to give the experts more time to study documents.
Saddam, wearing a dark suit and white shirt, sat in a metal pen listening quietly as the report was presented in court.
He could soon face a new trial on charges of genocide against the Kurds in the 1980s.