My Team

Sarah S. Miller regards clients' financial security among the most important issues – and so does her team of professionals that are focused on understanding and serving each individual client. Providing the best customer service is the cornerstone of our practice. Call whenever you have a question, concern or need. Sarah and her team are eager to help.

If you need to schedule an appointment, make changes to your policies or investments, or would like to request any other service, please let us know. We are excited to hear from you.


Katherine Horning, M.Sc.
Associate Financial Representative

Katherine Horning joined the team in 2015. She graduated from Newcastle Business School at Northumbria University in England with a Master's Degree in Marketing Management in 2009. Previously, Katherine graduated from California State University, Long Beach in 2006 with a Public Relations/Marketing degree. After moving to Colorado with her husband in 2014, Katherine met Sarah. Katherine provides excellent customer service and innovative solutions.

In Katherine's free time she enjoys spending time outdoors in the beautiful Colorado weather with her husband. She also loves working out at the gym and attending sporting events. Katherine also enjoys networking and spending time with family and friends.

Mitch Castillo
Associate Financial Representative


Mitch Castillo joined the team in 2016.  He graduated from Colorado Mesa University with a Bachelor's Degree in Business management in 2014.  He is a former Intern and Advisor at Northwestern Mutual. Mitch is an exceptional planner and provides innovative solutions. He is also Series 6 and 63 investment licensed. In Mitch's free time he enjoys spending time watching and playing sports, especially golf and basketball.  Mitch also enjoys spending time with his girlfriend, Jordyn, dog, Zeus and family and friends.


Sarah S. Miller

Financial Advisor

  • Office 303-390-5773
  • Mobile 970-443-7309

To learn more about Northwestern Mutual Investment Services, LLC and its financial representatives, visit: FINRA BrokerCheck