Mary Moriarty is the elected Hennepin County Attorney. Moriarty was elected in 2022 and previously served as the Hennepin County Chief Public Defender for 6 years (2014 – 2020). As the County Attorney, Moriarty serves as the chief executive of Minnesota’s largest public law office.

Moriarty grew up in New Ulm, Minnesota. Her mother, Linda, was an English teacher, and her father, Patrick, served as Itasca County Attorney from 1963-1969 and was later a public defender in New Ulm. After high school, Moriarty attended Macalester College, where she played softball and basketball and majored in history and political science, earning her Bachelor of Arts in 1986. In 1989, she earned a Juris Doctor from the University of Minnesota Law School. After clerking for Hennepin County Judge Kevin Burke, Moriarty joined the Hennepin County Public Defender's Office.

Early in her career as a public defender, Moriarty argued a case that would eventually go to the U.S. Supreme Court. A Minneapolis police officer had patted down a man and claimed that he could feel through the man's jacket that a small lump was crack cocaine, justifying the search. Moriarty argued that it would have been impossible to identify the lump as drugs. On June 7, 1993, the high court unanimously agreed, ruling that the officer had exceeded the limits of a legal pat-down. The case (Minnesota v. Dickerson) established what is referred to across the United States as the “plain feel doctrine.”

In 2014, after spending 25 years as a public defender, Moriarty was selected as Hennepin County's first female chief public defender. As chief, Moriarty oversaw some 45,000 cases per year and managed a staff of 140 attorneys and over 70 support staff including investigators, dispositional advisors, paralegals, IT personnel, legal office assistants and law clerks. An independent evaluation from the National Center for State Courts stated that under Moriarty's leadership, Hennepin County had one of the best public defender offices in the country, one that was as successful as a private law firm. Moriarty retired from the public defender's office in 2020.

During the trial of Derek Chauvin, Moriarty provided on-air legal commentary and analysis to various local and national media outlets including MSNBC, BBC, CBS, FOX, and TPT. 

Moriarty was elected County Attorney in 2022. As County Attorney, Moriarty manages a staff of over 500 people with an annual budget of $69 million. The County Attorney sets policies and priorities for prosecuting criminal cases, oversees child protection and child support cases, and provides legal advice and representation to county government. Hennepin County is the largest local government in Minnesota and has a $2.6 billion annual budget with 9,000 employees.