Judge Raouf Abdul Rahman, who sentenced Saddam Hussein to death, was captured and killed by former members of the Presidential Guard who joined the Islamic State in Iraq and the Levant (ISIL).
Originally from Halabja, Judge Abdul Rahman popularized the accusation that President Hussein had allegedly killed his own people with chemical weapons in 1988. Such disinformation was widely resorted to by the United States and Britain to justify the overthrow of President Hussein.  In fact, during the Iraq war against Iran, both sides made use of chemical weapons. It was a sudden change in wind during a battle that diverted the Iranian gas towards Halabja, killing at least 5,000 people. 
This vengeance confirms that the remaining officers of the former presidential guard joined the jihadists to fight together against the al-Maliki government.