Police said 20 gunmen broke into the house of Haidar Mohammed Ali Dajili, the director of Chalabi's office, in western Baghdad in the early morning hours Thursday to carry out the killing.
No group claimed responsibility for the assassination.
In Baaqouba, gunmen stormed the house of Iraqi soldier Ibrahim Omar and killed his wife and two of his children. Omar was not at home at the time of the attack in which also two other children were injured.
2014: The Year in Music [PHOTOS]