Meet the team
Gabriel Griess - CEO/Co-Founder
Gabriel Griess - CEO/Co-Founder
Gabriel Griess - CEO/Co-Founder
Accomplished Chief Executive; Retired Air Force C-130 Navigator (Disabled Veteran); MBA and MA in Foreign Policy; Married to his twin flame, Kristie; Three Amazing Kids – Preston 15, Mikayla 14, Harrison 11; Founder, “Navigating Leadership” Series.
Dr. Bill Rivard - Co-Founder
Gabriel Griess - CEO/Co-Founder
Gabriel Griess - CEO/Co-Founder
Dr. Bill Rivard is the founder & CEO of Matrix Providers founded in 2010 based on the commitment to attract the best of the best to ensure we take care of our military patients, who we think are some of the most important patients in the world.
Dr. Rivard is a retired Army Colonel with nearly 3 decades of military service and 25+ years of
Dr. Bill Rivard is the founder & CEO of Matrix Providers founded in 2010 based on the commitment to attract the best of the best to ensure we take care of our military patients, who we think are some of the most important patients in the world.
Dr. Rivard is a retired Army Colonel with nearly 3 decades of military service and 25+ years of experience in government contracting. He earned a Doctor of Optometry degree, a Masters of Business Administration and Fellowship in Executive Healthcare Management from Indiana University. He also earned a Bachelor of Science from University of Notre Dame. His career achievements also include acting as Chief of Staff for the Department of Defense’s largest overseas medical center.
Dr. Rivard lives in Boulder Colorado.
Tricia Brown – President/COO
Mike Horowitz - Chief Financial Officer
Mike Horowitz - Chief Financial Officer
Tricia has over 30 years of recruiting & staffing experience and 20 years in healthcare staffing including working with large global and publicly traded organizations, including AMN Healthcare, Cross Country Health & Randstad.
She has held key executive roles including SVP of Client Services, VP of Implementation & Workforce Solutions and VP of Credentialing Operations. Additionally, she held the role of VP Sales Operations for Locum Tenens, Physician Transition Management and Revenue Cycle Management.
Tricia is proud to have led a strategic initiative to mobilize healthcare workers during the COVID-19 health pandemic which secured the FEMA IDIQ award.
Tricia is based in St. Petersburg, FL
Mike Horowitz - Chief Financial Officer
Mike Horowitz - Chief Financial Officer
Mike Horowitz - Chief Financial Officer
Mike Horowitz has been a leader in Government Contracting since 2004 and in Healthcare specifically for the last year. He has been recognized for his contributions and efforts in achieving growth through competitive contract awards, process improvement, and driving organizational change to enhance capabilities. Mike embodies the core values of MedForceX, with his professionalism and competency, fostering trust and cultivating partnerships.
Kevin Sellers - Managing Director
Mike Horowitz - Chief Financial Officer
Kevin Sellers - Managing Director
Retired senior military officer (Disabled Veteran); 30 years of innovation results, business operations and leadership; Member of the Choctaw Tribe; Married to his beautiful wife, Angela, along with four children and 1 grandchild
Teresa Lund - Director, Program Management
Carmen Shoemaker - Director, Contracts & Purchasing
Carmen Shoemaker - Director, Contracts & Purchasing
Teresa joined Matrix Providers in 2018 and is our Director of Program Management. She has over 20 years of government contract experience including execution and maintenance of program management processes, delivery, data reporting and effectiveness. Teresa's experience with ADCMS and CLASS as well as DHA/MQS makes her the ideal professi
Teresa joined Matrix Providers in 2018 and is our Director of Program Management. She has over 20 years of government contract experience including execution and maintenance of program management processes, delivery, data reporting and effectiveness. Teresa's experience with ADCMS and CLASS as well as DHA/MQS makes her the ideal professional for her role which will help elevate MedForceX as a premier partner of choice.
Carmen Shoemaker - Director, Contracts & Purchasing
Carmen Shoemaker - Director, Contracts & Purchasing
Carmen Shoemaker - Director, Contracts & Purchasing
Carmen Shoemaker has been involved in government contracting since 2005, advancing through the ranks of various government contractors—from small startups to some of the industry’s largest leaders. With a diverse background supporting a wide range of programs, Carmen brings a wealth of expertise and skill, positioning her to foster strong, successful partnerships with MedForceX.