Kareen O'Brien

Associate Attorney

Maricopa County Attorney's Office

Kareen O’Brien has been practicing law since 2004. A graduate of Southwestern University Law School in Los Angeles, California, Kareen began her career in the areas of civil litigation and intellectual property rights’ enforcement. Eager to have more trial experience, in 2006 she became a Deputy District Attorney for the County of Los Angeles, where she eventually handled the most serious and violent family violence and sexual assault cases. In 2012, Kareen moved to Phoenix with her family, and became a member of the Arizona State Bar that same year. After a short time as a Deputy County Attorney with Maricopa County Attorney’s Office (“MCAO”) in their sex crimes bureau, Kareen decided to try something different, so she began practicing Family Law. In 2023, Kareen rejoined MCAO where she now works as a prosecutor in the Sex Crimes Bureau.