The Iraqi special tribunal has laid its first formal charge against former President Saddam Hussein.
Saddam could face the death penalty
It involves the killing of Shia Muslims in the village of Dujail, north of Baghdad, in 1982, after a failed assassination attempt against him.
This is not the most serious charge - only the one where the investigation has advanced most, says the BBC's Caroline Hawley in Baghdad.
A date for the start of the trial will be set in the next few days.
Saddam Hussein, who was ousted by US-led forces and captured in December 2003, faces the death penalty if convicted.
The tribunal's chief investigating judge, Raed Juhi, said the investigation into the Dujail case was complete.
The announcement means the former president could stand trial in early September.
Troops and helicopters attacked the Shia village 40km (25 miles) north of Baghdad after the assassination attempt failed.
Dujail killings, 1982
Massacre of Barzani tribe, 1983
Killing of religious leaders, 1974
'Ethnic cleansing' of Kurds, 1988
Gassing Kurds in Halabja, 1988
Invasion of Kuwait, 1990
Crushing Shia and Kurdish uprisings, 1991
Killing political activists
More than 140 residents were executed, hundreds more were tortured.
Apart from Saddam Hussein, his brother-in-law Barzan Ibrahim al-Hassan, former Vice-President Taha Yasin Ramadan, and former top judge Awad Badar al-Bender will be tried in connection with this case, Mr Juhi said.
"Hopefully, in the next few weeks, we look forward to concluding the investigation into other cases," he said, allowing other trials to go ahead.
The Iraqi government has said Saddam Hussein will face only 12 charges when he goes on trial, despite a possible 500 cases against him.
Some of the charges will concern the chemical attack on the Kurdish village of Halabja in 1988, the invasion of Kuwait in 1990 and the repression of Shias in 1991.