I was born into a military family.  My dad, Bill Kellner, served in the Marine Corps and his career kept my mom and the rest of our family on the move, growing up in homes from Virginia and North Carolina to Chile.  Even though the scenery changes in a military family, I was always well grounded in core family principles that guide me to this day: the importance of service, doing the right thing even when it’s hard, and always staying connected as a family.  As a lifelong Republican, my beliefs were molded by President Reagan.  I believe strongly in respecting the rule of law, small government, and fiscal responsibility. 

As a relatively young adult who watched 9/11 and the aftermath unfold, I knew I wanted to continue in my family’s proud tradition of military service.  After graduating from the University of Florida, I earned my commission as a Second Lieutenant in the United States Marine Corps.

Despite moving around as a ‘military brat’ my whole life, I had never been to Colorado.  I remember driving towards the law school in Boulder and seeing the mountains and just knowing, this is where I want to be.  I met my wife Sarah on our first day of school together, and the rest is history.  Colorado has been my home ever since those first days in the state, but after graduating law school, I still had more work to do in service to my country. 

For the first five years after graduating law school, I served on active duty in the Marine Corps from Quantico, Virginia, to San Diego, California.  I was promoted to Captain and held various prosecutorial roles, such as Senior Trial Counsel and Military Justice Officer, and Special Assistant U.S. Attorney for the Southern District of California.  During that time, I deployed to Afghanistan to join Regimental Combat Team 7 as the deputy judge advocate where my job was to help develop the rule of law in Marjah, an area overcome by violence and terrorism.  I partnered with the local Afghan prosecutor and government leaders to help resolve conflicts in the absence of a formal justice system, helped to build schools for girls who were previously denied access to education, worked to train the local police force, and participated in operational planning for military operations and local elections.

Sarah and I got married in Denver immediately after my return from Afghanistan.  In 2011, I left active duty, accepted a commission in the Marine Corps Reserves, which allowed Sarah and me to make Colorado our full-time and permanent home.  I began working as a civilian prosecutor, first for the Boulder County District Attorney, where I began to cultivate a specialization in cold cases.  One of those cases was People v. Michael Clark, a hard-fought 1994 cold case murder that resulted in a conviction and justice for the victim, Marty Grisham, that had been denied for nearly two decades. 

When George Brauchler was elected in 2012, he contacted me to start a Cold Case Unit that would tackle the 18th Judicial District’s backlog of unsolved homicide cases. Since that unit was founded, we’ve had unprecedented success in solving cases and prosecuting offenders in the pursuit of justice for victims that was previously deemed unattainable. Some of those cases include:

While much of my time in the 18th Judicial District has been focused on high profile homicide cases, I’ve also tackled other issues in our community, including leading an investigation of children overdosing on Spice in our community.  I was a founding member of the Veterans Treatment Court to help veterans in the justice system deal with service-related trauma.  I was recognized as the “Prosecutor of the Year” by the Colorado District Attorney’s Council in 2016; the highest recognition for a prosecutor in the state.  In 2018, I was recognized as a member of the “Prosecution Team of the Year” by MADD for my work in convicting a drunk driver of second degree murder for hitting and killing 22 year-old Dalton McCreary as he walked in a crosswalk in Aurora. 


As a Chief Deputy District Attorney, I previously supervised the largest team of dedicated felony prosecutors handling literally thousands of cases in Arapahoe County, and I am currently the Chief Deputy District Attorney in charge of supervising and managing all of the 18th Judicial District's prosecution activities in Douglas, Elbert and Lincoln Counties.  My most recent murder trial was against Mikhail Purpera, a felon from Louisiana who came to our community intent on violence and drug dealing.  Purpera was convicted of first-degree murder for the senseless killing of a young man in Englewood.

Throughout my years as a prosecutor, I have continued my service in the Marine Corps Reserve, rising to the rank of Major and now selected for promotion to Lieutenant Colonel. I currently serve as an Operational Law Attorney with NORAD-USNORTHCOM in Colorado Springs, where I provide support for disaster relief operations. My military decorations include the Meritorious Service Medal, Navy and Marine Corps Commendation Medal (2), Presidential Unit Citation, Navy Unit Commendation (2), National Defense Service Medal, Afghanistan Campaign Medal (2), Global War on Terrorism Service Medal, Sea Service Deployment Medal, and NATO-ISAF Medal.

I am dedicated to public service and representing the People of Arapahoe, Douglas, Elbert, and Lincoln counties in court. My approach to prosecution is straightforward: do the right thing, at the right time, for the right reasons. For more information about my vision for the 18th Judicial District, click below:


John at Officer Candidate School (left), Colonel Bill Kellner (middle), Lieutenant Andrew Kellner (right).

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Registered Agent: Marge Klein




Use of John Kellner's military rank, job titles, and photographs in uniform does not imply endorsement by the United States Marine Corps or the Department of Defense.

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