Dr. Theeler graduated from Black Hills State University (Summa Cum Laude) in Spearfish, South Dakota in May 2001. He was directly commissioned into the United States Army as a Second Lieutenant in June 2001. 2LT Theeler attended the Uniformed Services University, F. Edward Hebert School of Medicine (Alpha Omega Alpha) from 2001 to 2005. Captain Theeler completed internship and residency training at Madigan Army Medical Center in Adult Neurology from 2005 to 2009.

Captain Theeler served as Chief, Department of Neurology at William Beaumont Army Medical Center from 2009 to 2010. From 2010 to 2012, he completed fellowship training in Neuro-Oncology at the University of Texas, MD Anderson Cancer Center in Houston, Texas.

In 2012, Major Theeler was stationed at Walter Reed National Military Medical Center in the Department of Neurology. From 2012 to 2021, he served in multiple GME and leadership roles at WRNMMC including Associate Residency Program Director, Deputy Chief, and Chief, Department of Neurology.

LTC Theeler was named Chair, Department of Neurology at the Uniformed Services University on June 1, 2021. He holds the academic rank of Professor in the Department of Neurology at USUHS.

COL Theeler has an active, Neuro-Oncology practice at the John P. Murtha Cancer Center located within WRNMMC. He is a Clinical Collaborator in the National Institutes of Health, National Cancer Institute, Neuro-Oncology Branch in Bethesda, MD.

Dr. Theeler’s research focuses on rare primary central nervous system neoplasms including pilocytic astroctyomas, pleomorphic xanthoastrocytomas, diffuse midline gliomas and other brain cancers that have an increased incidence in adolescent and young adult populations.