The Fairfax County Board of Supervisors appointed Arnold as Deputy County Executive for Safety and Security at its meeting on Feb. 22, 2022. 

“I’m excited about the opportunities that lay ahead as public safety continues to evolve,” Arnold said. “I will be focused on exploring ways to further integrate safety and security across all aspects of our work as a county and I look forward to a close, collaborative relationship with the community.”  

Until last week,Arnold was the Fairfax County Fire and Rescue Department's (FRD) assistant fire chief since 2020. Arnold will replace David Rohrer who recently retired after 41 years with Fairfax County. Rohrer served as as Fairfax County Chief of Police for eight years

Successful programs like Diversion First, with partnerships at their foundation, are a model for what I hope we can accomplish. I will also be placing an emphasis on reducing risk in the community, to help prevent emergencies and the need for emergency services. With direction from the Countywide Strategic Plan, equity at the center of our decisions, and the solid strategic work already being done in public safety and security agencies, we will continue to provide the highest quality public safety service to our community.

Arnold will oversee the Police Department, the Fire and Rescue Department, the Department of Emergency Management and Security, the Department of Public Safety Communications and the Department of Animal Sheltering  … He will receive an annual salary of $215,000, according to Fairfax County. 

He worked as senior advisor to the chief and liaison to other county departments. Arnold supervised the Fiscal Services Division, Data Analytics Strategy Management Division, Information Technology Division, Public Information Office, Health and Wellness Section, and Planning Section of the FRD.

Arnold holds numerous certifications, never stopping learning. Three years ago, he was awarded the Executive Fire Officer designation from the National Fire Academy. The program reportedly "is intense and involves taking four graduate and upper-division-baccalaureate equivalent courses over a four-year period," according to a post on  FRD’s Facebook page. Additionally, Arnold has received several performance and accomplishment awards for his service. Arnold published papers on topics relating to fire and rescue.

Arnold began Fairfax County career 21 years ago as a firefighter in 2001. He advanced through the ranks to become a lieutenant, captain, battalion commander, and deputy chief. Arnold received a Master of Science in executive fire service leadership from Grand Canyon University. He holds a Bachelor of Science in business administration from Pennsylvania State University.