Ali Hassan al-Majid, better known to the world as 'Chemical Ali', was executed by hanging Monday after receiving four death sentences for genocide and crimes against humanity. From BBC

Majid was first sentenced to hang in June 2007 for his role in a military campaign against ethnic Kurds, codenamed Anfal, that lasted from February to August of 1988.

In December 2008 he also received a death sentence for his role in crushing a Shia revolt after the 1991 Gulf War.

In March 2009 he was sentenced to death, along with others, for the 1999 killings of Shia Muslims in the Sadr City district of Baghdad.

The BBC goes on to say al-Majid could have been executed earlier after receiving his first death sentence, but that it was important to Iraqi Kurds that he catch a dirt nap for his Halabja attack.