The Ketaeb Hezbollah paramilitary group handed over the body of a man suspected of being Saddam Hussein's long-fugitive deputy Izzat Ibrahim al-Douri to Iraq's government on Monday for further testing.
Killing Douri -- who was vice president at the time of the 2003 U.S.-led invasion and has for years been the most senior member of Saddam's regime still at large -- would be a major victory for Baghdad.
Ketaeb Hezbollah says the man killed by pro-government forces on Friday was Douri, but he had previously been reported dead only to resurface in audio and video messages.
"Today, we handed over the body of the criminal Izzat al-Douri to the Iraqi government" after confirming his identity with "tests and also testimony from those who previously met him", Ketaeb Hezbollah spokesman Jaafar al-Husseini told journalists.
Husseini told AFP the day before that two men captured by Ketaeb Hezbollah who had seen Douri in the past six months said the dead man was him, but that account could not be independently confirmed.
Ketaeb Hezbollah -- one of the most powerful militias fighting alongside government forces against the ISIS -- delivered the body in a heavily armed convoy of dozens of vehicles to a blocked-off section of street in central Baghdad.
A health ministry official, speaking on condition of anonymity, confirmed it had received the body and would conduct DNA testing.
Ghanim Abdulkarim Ghanim, a human rights ministry official, had earlier said the government would use available files on Douri to determine whether it was him.
If necessary, it would seek to compare a blood sample to that of a relative, or identify the body by its physical features.
Husseini, speaking on a Ketaeb Hezbollah-affiliated television station on Sunday, said the man believed to be Douri was killed near the town of Al-Alam north of Baghdad, and his body later transferred to the militia.
That account squared with one from Omar Abdullah al-Jbara, a leader in the volunteer forces from Al-Alam, who said local fighters and police clashed with a group of men on Friday, killing 12, including one who resembled Douri.
The Army of the Men of the Naqshbandiyah Order -- known by its Arabic initials JRTN and believed to be close to Douri -- took part in a sweeping ISIS-led militant offensive that overran large areas north and west of Baghdad last June.
But little has been heard from JRTN and other groups since, with ISIS dominating the conquered territory.
Senior members of Saddam's Baath party, to which Douri belonged, have also reportedly played a major role in ISIS itself.