BAGHDAD, Iraq - Iraq's prime minister ordered an investigation Tuesday into Saddam Hussein's execution to try to uncover who taunted the former dictator in the last minutes of his life, and who leaked inflammatory footage taken by camera phone of the hanging.

The unofficial video, on which at least one person is heard shouting “To hell!” at the deposed president and Saddam is heard exchanging insults with his executioners, dealt a blow to Iraq's efforts to prove it was a neutral enforcer of the law. Instead, the emotional, politicized spectacle raised tensions between the Shiite majority and Sunni Arabs who ran the country until their benefactor, Saddam, was ousted in the U.S.-led invasion of 2003.

A prosecutor who saw the hanging said some of the taunting came from guards outside the execution chamber, not the masked ones who put the noose around Saddam's neck.

The Iraqi government did not say what, if any, punishment would await anyone uncovered in its probe of guards and 14 selected witnesses who attended the execution at a Baghdad prison before dawn Saturday. Some were high-ranking officials or people affiliated with radical Shiite cleric Muqtada al-Sadr, a political ally of Prime Minister Nouri al-Maliki, who had wanted to speed up the timing of the execution after an appeals court upheld the death sentence.