Aldenberg will become chief military and veterans services officer for Easterseals of New Hampshire and Vermont, overseeing operations of the military and veterans campus under development in Franklin. The site is expected to open next summer.
Manchester Mayor Jay Ruais said Marr will be sworn in at a ceremony "in the very near future" that will include additional department promotions.
Marr has served as a law enforcement professional for 24 years. He began his career in 2000 as a patrol officer with the Montgomery County Police Department in Silver Spring, Maryland, before joining the Manchester department in 2003.
Marr is a 2001 graduate of the Montgomery County Police Academy, and completed additional training at the New Hampshire Police Standards and Training Academy in 2003.
Marr has served as Aldenberg's second-in-command for two years.
In nominating Marr for the position, Ruais said he's found him to be an "outstanding, approachable and thoughtful professional."
"In our conversations, he understands the seriousness of the position of chief and the dedication necessary to lead the state's largest municipal police force," Ruais said. "As a 21-year veteran of the force, Assistant Chief Marr is uniquely aware of the challenges our city faces. He also has valuable insights into the over 300 officers he will lead if given the opportunity."
Ruais said Marr's leadership skills, knowledge of tactical operations and investigations, crisis management experience, and personnel management "give him a solid foundation to continue to be successful at the next level."
"I have every confidence he will hold himself and his officers to the highest standards, always staying true to every police officer's sworn duty to protect and serve," Ruais said.
Marr earned a Bachelor of Arts degree in Middle Eastern history, with a minor in political science, from the University of New Hampshire. Over the course of his career he has also attained certification in a number of specialized training programs, including certification as a polygraph examiner, which he attained from the Northeast Counter Drug Training Center.
He is a veteran of the U.S. Marine Corps. He served from 1992 to 1996 as a squad leader with 2nd Battalion 2nd Marines and was honorably discharged at the rank of corporal. He served in Operation Uphold/Support Democracy in Haiti and Operation Assured Response in Liberia.
During his tenure with MPD, Marr has served as a patrol officer and as an investigator, beginning with an assignment to the Domestic Violence Unit and then in 2009, as a member of the Detective Squad. He was promoted to sergeant in 2015, first assigned to patrol as a street supervisor, then supervisor of the Domestic and Sexual Violence Unit, a lieutenant and assistant chief.
Marr has received several awards over the course of his career.
In 2004, he was awarded the department's Life Saving Medal for assisting in evacuating residents from a burning building. He also received a N.H. Congressional Law Enforcement Medal for that same action.
In 2007 he received the department's Honorable Service Medal recognizing his actions during and after the fatal shooting of Officer Michael Briggs in 2006.
In 2012, he was awarded the Meritorious Service Medal in recognition of his actions related to the apprehension of the armed suspect in the shooting of Officer Dan Doherty.
In 2014, Marr was commended for his work related to a burglary initiative implemented in the fall of 2013, which culminated in the arrest of several people and the recovery of stolen property worth tens of thousands of dollars.
He was named the Officer of the Month for September and later named Officer of the Year for 2014.
In 2017, he was awarded a Life Saving Medal in recognition of his rendering medical aid to a man who had suffered a heart attack in the lobby of the police station.